
(lass r)>tjjf 

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ISSUED JULY 31, 1912 

HAWAII AGRICULTURAL EXPERIMENT STATION 
E. V. WILCOX, SPECIAL AGENT IN CHARGE 



PRODUCTION AND INSPECTION 

OF MILK 



BY 

E. V. WILCOX 
SPECIAL AGENT IN CHARGE 



Honolulu: 
Honolulu Stak-Bullettn, Ltd. 
1912 



HAWAII AGRICULTURAL EXPERIMENT STATION 
E. V. WILCOX, SPECIAL AGENT IN CHARGE 



9*f 



PRODUCTION AND INSPECTION 

OF MILK 



BY 

E. V. WILCOX 
SPECIAL AGENT IN CHARGE 



honoivulu: 
Honolulu Star-Bulletin, Ltd. 
1912 



°7 ^ 



HAWAII AGRICULTURAL EXPERIMENT STATION, HONOLULU. 

( Under the supervision of A. (J. True, Director of the Office of Ex- 
periment Stations, United States Department of Agriculture.) 

Walter H. Evans, Chief of Division of Insular Stations, Office of Ex- 
periment Stations. 

STATION STAFF. 

E. V. Wilcox, Special Agent in Charge. 
J. Edgar Higgins, Horticulturist. 

W. P. Kelley, Chemist. 

0. E. McClelland, Agronomist. 

I). T. Fullaway, Entomologist. 

W. T. McG-eorge, Assistant Chemist. 

Alice E. Thompson, Assistant Chemist. 

0. J. Hunn, Assistant Horticulturist. 

V. S. Holt, Assistant in Horticulture. 

C. A. Sahr, Assistant in Agronomy. 

F. A. Clowes, Superintendent Hawaii Substations. 
W. A. Anderson, Superintendent Rubber Substation. 

J. deC. Jerves, Superintendent Homestead Substation. 
J . K. Clark, Superintendent Waipio Substation. 



n, ft? % 



TABLE OF CONTENTS. 

Page. 

Normal milk 5-31 

Biology of milk 5 

Anatomy of the udder ..... 5 

Physiology of milk secretion 6 

Bacteria in milk 8 

Enzymes in milk 8 

Leucocytes in milk 9 

Germicidal substances in milk 10 

Physical properties of milk 11 

Color 11 

Specific gravity 11 

Viscosity 11 

Odor 12 

Microscopic appearance 12 

Specific heat 12 

Freezing point 13 

Density 13 

Refractive index 13 

Cohesive power 13 

Electrical properties 13 

Basis of creaming methods 13 

Chemistry of milk 14 

Reaction 14 

Composition 14 

Pat 14 

Casein 15 

Lactalbumin 15 

Lactoglobulin 16 

Galactin 16 

Milk sugar 16 

Mineral constituents 16 

Other substances 17 

Factors influencing composition 17 

Breed 17 

Age of cow 18 

Period of lactation 18 

Individuality 18 

Manner and time of milking 19 

Exercise and work 20 

Spaying 20 



IV 

Page. 

Estrum 20 

Weather 20 

Seasons 21 

Disease 21 

Excitement 21 

Peed 21 

Freezing 23 

Shelter and care of cows 23 

Dehorning cows 23 

Size of cows 23 

Gestation 23 

Mixing milk 23 

Drugs 24 

Method of drawing from can 24 

Legal standards 24 

Market milk 25 

Commercial forms of milk 27 

Standard milk 27 

Standardized, blended milk 27 

Modified, humanized milk 28 

Certified milk 28 

Guaranteed milk 28 

Sanitary milk 29 

Sterilized milk 29 

Clarified milk 29 

Carbonated' milk 29 

Homogenized milk 29 

Condensed, evaporated milk 29 

Desiccated milk 29 

Milk of mammals other than cows (human, ewe, 
goat, reindeer, hog, mare, ass, mule, camel, In- 
dian buffalo, zebu, dog, cat, porpoise, rabbit, ele- 
phant etc.) 30 

II. Abnormal milk 35-52 

Abnormal composition 32 

Abnormal colors 33 

Added coloring matters 33 

Colors due to bacteria 33 

Blue milk 33 

Red milk 34 

Yellow milk 34 

Other colors 34 

Abnormal flavors and odors 34 

Due to feeding stuffs 34 



V 
Page. 

Absorption of odors 37 

Due to bacteria 37 

Bitter milk 37 

Soapy milk 38 

Sour milk 38 

Alcoholic fermentation 39 

Ropy or slimy milk 39 

Abnormalities d'ue to condition of udder 40 

Abnormalities due to ingestion of drugs and harm- 
ful plants 43 

Pathogenic bacteria in milk 45 

Toxins, antitoxins etc. in milk 45 

Bacterial changes, milk poisoning 46 

Milk during estrum 47 

Leucocytes in milk 47 

Dirt in milk 51 

Adulerations 52 

III. Hygiene and diseases of cows 53-98 

Exercise 53 

Grooming 54 

Regularity in care 54 

Feeding 54 

Bedding 55 

Water 55 

Salt 59 

Disinfection 59 

Diseases of cows 64-98 

Abortion 64 

Actinomycosis 65 

Actinobacillosis 65 

Anthrax 66 

Blackleg 66 

Bloating 67 

Cornstalk disease 68 

Cowpox 69 

Enteritis 69 

Flukes 70 

Foot-and-mouth disease 71 

Foot rot 72 

Hematuria 72 

Hemorrhagic septicemia 73 

Horn fly 73 

Jaundice 74 

Joint-ill 74 



VI 

Page. 

Keratitis 75 

Lice 75 

Malignant catarrhal fever 76 

Malignant edema 77 

Mammitis 77 

Metrics 79 

Milk fever 79 

Milk sickness 81 

Mycosis 81 

Nagana 82 

Nephritis 82 

Nodular disease 83 

Osteomalacia 83 

Pericarditis 84 

Peritonitis 84 

Pleuro-pneumonia 85 

Poisons 85 

Rabies 87 

Retention of afterbirth 88 

Rheumatism 88 

Rinderpest 89 

Ringworm 89 

Scabies ' 90 

Scouring 91 

Screwworm fly 91 

Staggers 92 

Stomach worms 92 

Stomatitis 92 

Teat diseases 93 

Texas fever 94 

Tuberculosis 95 

Tumors 96 

Verminous bronchitis 97 

Warble fly 97 

Wounds 98 

IV. Feeding cows 99-105 

Grains for cows 99 

Narrow and wide rations 100 

Size of grain rations 101 

Succulent feeds 101 

Pasture 101 

Soiling 102 

Silage 102 

Roots and fruits 102 



VII 

Dry roughage 1°3 

Miscellaneous feeds 104 

Sample rations 1 ^ 4 

V. Buildings and premises 106-115 

Stables !0 6 

Ventilation 106 

Sheds 109 

Bedding HO 

Barnyards m 

Sewage disposal Ill 

Milk rooms 112 

Inspection of buildings and premises 114 

VI. Milking and handling milk on the farm 116-140 

Health and habits of attendants 116 

Cleanliness in milking, cleaning cows 119 

Methods of milking 120 

Ordinary method 120 

Hegelund method 121 

Milking machines 123 

Rejecting foremilk 127 

Use of covered pails 128 

Straining, filtering, purifying, aerating and cooling 

milk 129 

Care of dairy utensils 133 

General care of milk 136 

VII. Transportation and sale of milk 141-149 

Means of transportation 141 

Milk supply of New York City 142 

Milk supply of Boston 144 

Milk supply of Philadelphia 145 

Milk supply of other cities 146 

Concentration and cooperation in milk business.. 147 

VIII. Refrigeration 150-161 

Effects of freezing and' refrigeration on milk 150 

Methods of refrigeration 151 

Ice 152 

Brine system 153 

Ammonia machines and other artificial methods 154 

Ice-milk or frozen milk 157 

Cold storage of butter 159 

Cold storage of cheese 159 

Condensed milk and milk sugar obtained by freezing 160 

IX. Pasteurization and sterilization of milk 162-168 

Apparatus and methods of pasteurization 162 



VIII 

Effect on biology of milk and bacteria 164 

Effect on pbysics of milk 165 

Effect on chemistry of milk 166 

Effect on digestibility of milk 166 

X. Preservatives in market milk 169-176 

Kinds and' extent of use 169 

Formaldehyde 169 

Boric acid and borax 171 

Hydrogen peroxid 173 

Other preservatives 174 

Sodium carbonate 174 

Benzoic acid 175 

Chromates 175 

Saccharin 175 

Salicylic acid 175 

Fluorids etc 175 

Proprietary preservatives 176 

Conclusions on use of preservatives 176 

XI. Physical and chemical examination of milk 177-197 

Testing cows for dairy purposes 177 

Examination of market milk 178 

Taking, preserving and caring for samples 178 

Composite samples 179 

Sampling cream 180 

Determination of specific gravity 181 

Quevenne lactometer 181 

N. Y. Board of Health lactometer 181 

Pycnometer 182 

Determination of fat 182 

The Babcock test 182 

Gerber acidobutyrometer 183 

Other volumetric tests 183 

Areometer test of Soxhlet 183 

Adams method 184 

Babcock asbestos method 184 

Paper coil method 184 

Densimetric method 184 

Refractometer 185 

Total solids 185 

Total proteids 185 

Casein 185 

Albumin 186 

Milk sugar 186 

Official method 186 

Fehling's solution 187 



Ash 



IX 



187 



Other constituents 188 

Acidity 188 

Mann's acid test I 88 

Farrington's alkaline tablet test 188 

Van Norman's alkali test 189 

Detection of preservatives and colors 189 

Boric acid and borates 1 8 9 

Formaldehyde I 89 

Benzoic acid 190 

Salicylic acid I 90 

Sodium carbonate 190 

Fluorids l y 

Foreign colors 191 

Annatto m 

Analin orange 191 

Caramel 192 

Detection of heated milk, dirt, adulterants etc 192 

Heated milk 192 

Added water 192 

Wisconsin curd test 193 

Gerber's fermentation test 193 

Dirt iy4 

Starch 194 

Gelatine I 94 

Cream thickeners 194 

Testing milk products for fat 194 

Condensed milk 194 

Cream 195 

XII. Bacteriology of milk 198-250 

Nature and classification of bacteria 198 

Reproduction of bacteria 199 

Changes produced by bacteria 200 

Factors affecting bacteria 202 

Sources of bacteria in milk 205 

Normal udder 205 

Diseased udder 205 

Exterior of cow 206 

Air • 207 

Milker 208 

Milk utensils 208 

Stables 208 

Barnyards 2 °9 

Bedding 209 



Water 209 

Contamination in handling 209 

Germicidal action of milk 210 

Classification of milk bacteria 211 

Pathogenic bacteria in milk 213 

Descriptive list of ordinary milk bacteria 215-237 

Extent of bacterial contamination 237 

Temperature and bacterial content of milk 239 

Time factor in bacterial content of milk 240 

Antagonism between bacterial species 241 

Means of reducing number of bacteria 241 

Growth of bacteria in milk 242 

Souring of milk 242 

Abnormal fermentations 244 

Streptococci in milk 245 

Comparative growth of bacterial species 245 

Methods of bacteriological examination 246 

Culture media 246 

Quantitative examination 247 

Choice of culture media 248 

Qualitative examination 249 

Examination of air 249 

Examination of water 249 

Boston method of examining milk 249 

XIII. Transmission of infectious diseases by milk 251-272 

Bovine diseases which may render milk toxic or 

pathogenic 2*51 

Tuberculosis 251 

Foot-and-mouth disease 257 

Anthrax 259 

Cowpox 260 

Rabies 260 

Tetanus 261 

Pleuro-pneumonia 261 

Actinomycosis 261 

Milk sickness 261 

Mammitis 262 

Milk fever 263 

Hemorrhagic enteritis 263 

Septic diseases 264 

Milk-borne diseases 266 

Typhoid fever 266 

Scarlet fever 268 

Diphtheria 269 



XI 

Cholera 270 

Thrush 271 

Diarrhoea 271 

Other diseases 271 

XIV. Dietetics of milk with reference to infant feeding. .. .273-296 

Mortality 273 

Physiology of mother's milk 276 

Mother's milk 277 

Wet nurse 281 

Cow's milk, a comparison 281 

Review of feeding methods 283 

The simple feeding case 289 

More difficult case 291 

Pasteurization, boiling and sterilization 293 

Charities and municipal control 295 

XV. Milk products in their relation to health . . 297-307 

Standards 297 

Hygienic relations 298 

Cream 298 

Skim milk 299 

Butter 299 

Cheese 302 

Condensed milk '. . . 303 

Milk powder 304 

Miscellaneous milk products 305 

Buttermilk 306 

Ice cream 306 

Leben 306 

Yauert 307 

Carbonated milk 307 

XVI. History of milk inspection 308-315 

Foreign countries 308 

United States 313 

XVII. Bibliography of milk inspection 316-343 



PREFACE. 

Milk is unquestionably the most important of all foods. Infants 
and young children depend upon it almost exclusively for sustenance 
and growth. Milk enters into the daily ration of nearly every adult 
person, particularly in the United States. The daily per capita con- 
sumption of milk ranges from one half pint to one pint in different 
cities. Milk is an ideal food, containing in a readily digestible form 
and in proper proportions all the elements of a complete, balanced 
ration. It is universally recognized as peculiarly adapted for the 
nourishment of children, invalids and convalescents. 

Recent investigations have shown the necessity of Federal, State 
and municipal control of food products. Such control is particularly 
important in the case of milk for reasons that nearly all kinds of bac- 
teria grow and multiply in milk, that in the ordinary method of 
handling it is exposed repeatedly to contamination, that milk sugar 
and casein are easily decomposed into disagreeable or dangerous pro- 
ducts, that milk is consumed in largest quantities by children and 
invalids who are most susceptible to such products, that milk may 
carry infections diseases, that milk may be deliberately adulterated 
or treated with preservatives, and that the consumer can detect none 
of these abnormal conditions except souring, which is the least harmful 
of all. 

Pure milk is obtained by milking healthy well-groomed cows in 
clean, sanitary surroundings, in thoroughly cleansed pails, and then 
cooling the milk to 50°F. or lower, and bottling it or pouring it into 
tightly closed cans without allowing any contamination to occur from 
the milkers or other source. Legal phraseology is always ponderous and 
mystifying and milk inspection regulations may seem unnecessarily 
complicated. Nevertheless, the only fundamental idea is cleanliness 
and this idea is easily understood. Healthy cows, healthy attendants, 
wholesome feeding stuffs, clean water, clean milk utensils, and clean 
habits are the only requisites. This may be further reduced to two 
terms, the proper conception of cleanliness and the desire to be cleanly. 

An ideal system of milk inspection includes a veterinary inspection 
of cows, stables, water supply and surroundings ; a supervision of milk 
rooms, milk utensils and methods of cleaning them ; supervision of 
methods of cooling milk and their effectiveness; control of the health 
and personal habits of the milkers; determination of the temperature 
at time of delivery, specific gravity, fat, total solids, acidity, presence 
of preservatives, and bacterial content. The mere laboratory examina- 
tion of samples of milk taken from dealers is not sufficient. 

The cost of milk production has increased in recent years. ISTew 
equipment to meet the requirements of health officers is an added bur- 



den to the milk producer, who may reasonably expect more for his 
milk after the cost of production lias increased. At present the con- 
sumer has too little real interest in a pure milk supply. We of I en 
hear the milk consumer talk glibly about sanitary milk, and at the 
same time rebel against paying a higher price for such milk. How 
can we expect the milk producer to increase his expenses all along the 
line from the cow to the consumer, if he is compelled to sell his milk 
for the same price as milk produced more cheaply and under less san- 
itary conditions? There have been several discouraging experiences 
along this line. In one instance a philanthropist established a modiel 
dairy where milk was produced under ideal sanitary conditions and 
with a remarkably low bacterial content. The public manifested no 
interest in the movement and showed no preference for sanitary milk 
over ordinary milk at the same price. The project was therefore 
abandoned. 

The purpose of the present volume is partly educational and, partly 
practical. It is hoped that the milk producer may gather from it a 
conception of what constitutes pure milk and definite suggestions as 
to how to produce such milk. It is even more earnestly hoped that 
the milk consumer will more clearly realize the value of pure milk and 
appreciate the extra expense of producing such milk, at least to the 
extent of being willing to pay more for it than for ordinary milk. 

More or less effective regulations for milk inspection have been 
adopted in nearly every city of the United States. The inspector in 
enforcing these regulations requires veterinary, engineering and chem- 
ical knowledge and, much tact as well as practical experience in 
dairying. 

In order that the sanitary regulation of milk may be accomplished 
most fully it is necessary that the milk producer, the milk consumer 
and the milk inspector should come to a mutual understanding of one 
another's problems and difficulties, and cooperate in a cordial and 
earnest manner. In working to accomplish this purpose the author 
has reviewed the field of literature on milk and has presented, the es- 
sential points in the light of personal experience. The dairyman will 
find a statement of approved methods of feeding and caring for cows, 
treating their diseases, handling, transportation, sale, refrigeration 
and pasteurization of milk. The inspector will find a statement of 
the normal and abnormal properties of milk, the symptoms of bovine 
diseases, the sanitary requirements of buildings used for dairy pur- 
poses, methods of testing and analyzing milk, detecting preservatives 
and adulterants, and the bacteriological study of milk. The milk 
consumer will obtain information on the dangers from impure milk, 
on the nature of the work of the milk inspector, and on what it means 
to produce pure milk. 

Most of the data recorded in this report are drawn from experience 
on the mainland, in the old dairy sections. Dairy conditions in Hawaii 



are different in many respects. The ease with which green fodder 
can be had the year around is an advantage. In almost every other 
respect the Hawaiian dairyman is at a disadvantage as compared 
with the mainland dairyman. Cows give less milk in tropical cli- 
mates — in Hawaii from four to seven quarts per day. All grains are 
considerably higher in price. The cultivation of the soil and the rais- 
ing of green crops are more expensive. The prevalence of the horn 
fly is a much more serious matter than on the mainland. The most 
reliable figures on the actual cos I of producing milk in Hawaii have 
been collected by Mr. P. M. Pond, who finds the cost to range between 
H and 9 cents per quart, not including the cost of delivery. Under our 
present conditions it would seem that the dairyman can not make a 
reasonable profit on sanitary milk delivered to the consumer at a lower 
price than 15 cents per quart. 

The inspection of dairies carried on under the supervision of Dr. 
V. A. JNTorgaard, territorial veterinarian, has been a very efficient 
means of raising the sanitary standard of our dairies, and of safe- 
guarding the public against the dangers of bacterially infected milk. 
Dr. INTorgaard has brought the intradermal test for tuberculosis to a 
striking degree of efficiency and reliability. 

The vital relation which exists between a sanitary milk supply and 
the health of infants made it seem desirable to include in this report 
a chapter on dietetics of milk with reference to infant feeding. This 
chapter has been written by Dr. Louise Taylor-Jones, a specialist in 
the diseases of children. There is a peculiar need of careful super- 
vision of the milk supply for children in tropical climates. The recog- 
nition of this truth, is coming to fruition in the work of the Palama 
Settlement, and other public-spirited men in Honolulu. 



CHAPTER I. 

NORMAL MILK. 

Milk is the secretion of the udder of the female mammal. Tn a 
commercial sense milk means cow's milk unless otherwise specified. 
The milk of mares, asses, goats and sheep is also used to a limited 
extent in this country and to a much greater extent in Europe and 
Asia. Normally milk is secreted only by the female after parturition, 
but occasionally males, castrated males, virgin females and young 
animals yield more or less milk. Thus quite frequently buck goats, 
castrated goats and new-born children produce small quantities of 
milk. Tn certain parts of Europe pregnant heifers are regularly 
milked, but this procedure weakens the heifers and lowers the milk 
yield after parturition. Virgin female dogs, young colts and mare 
mules have also been known to give milk. In a few instancese mare 
mules have given two or three quarts per day continuously for three 
or four years. 

Biology of Milk. 

Anatomy of the cow's udder. — The udder is suspended from the 
pubic region and consists of two halves. The skin over the udder 
is rather finer than that of the body as a. whole. A considerable por- 
tion of the skin of the udder is not covered with hair. There is an 
abundant accumulation of fat in the udder of the heifer and in the 
connective tissue at either end of the cow's udder. A two-layered 
wall of connective tissue separates the right and left halves of the 
udder. There is no special anatomical structure separating the an- 
terior and posterior quarters. Nevertheless each quarter is a distinct 
part of the mammary gland not communicating with any other quarter 
by blood vessels, lymph vessels or milk ducts. The independence of 
each quarter is clearly demonstrated in administering infusions 
through the teats, and also in the course of mammary diseases. In- 
fusions in one quarter do not penetrate into the other, and disease in 
one quarter does not affect the milk of any other quarters. 

The true secretory parenchyma of the udder is arranged in lobes 
composed of several lobules which in turn are subdivided into numer- 
ous yellowish or yellowish red alveoli. The various parenchymatous 
structures are held in place and supported by connective tissue in 
which are found the blood vessels, lymph vessels, nerves and milk 
ducts. The connective tissue framework also contains fat tissue. 
With advancing age the connective tissue increases in amount as the 



6 

parenchyma decreases. The efferent milk ducts from the individual 
alveoli gradually unite into larger ducts, finally emptying into the 
milk cistern. 

Each quarter normally has one teat but occasionally there are super- 
numary non-functional teats. The milk cistern is partly closed toward 
the teat by a rosette with 5-8 folds. The mucous membrane of the 
milk cistern bears a large number of folds and ridges connecting with 
one another like grill work. The true secretory tissue is arranged in 
the form of glandular tubes enlarged here and there into alveoli. The 
mammary gland is therefore both tubular and acinous. In the virgin 
heifer the epithelial cells of the glandular tissue grow out into long 
processes which fill up the lumen of the alveoli. During the first 
pregnancy these processes grow still larger, and branch into clavate 
endings. When the epithelial cells prepare for secretion they become 
finely granular and sharply delimited toward the lumen. Their form 
is then cylindrical. Small protoplasmic processes which extend into 
the lumen show a finely granular structure and contain minute fat 
globules. At the same time the epithelial cells show mitotic changes 
and other forms of activity. Leucocytes collect in the connective tissue, 
some of them penetrating into the alveolar lumen. With the com- 
mencement of secretion the lumen of the alveoli enlarges and becomes 
filled with fat globules which later coalesce into larger drops. Por- 
tions of the cell protoplasm are also discharged into the lumen to- 
gether with fluid from the cells and blood. In an active stage of 
lactation the alveolus is darker colored than when at rest. Moreover 
in a resting condition there is a smaller quantity of secretion, the pro- 
toplasma is more often striated, more mitotic figures are to be seen 
and leucocytes are more numerous. In active lactation the lumen of 
the alveoli is filled with innumerable fat globules, casein, leucocytes in 
a stage of fatty degeneration, particles of protoplasm and according 
to Rievel also amylaceous bodies which are very resistant to both acids 
and alkalis. 

The blood vessels of the udder are connected with the external pudic 
arteries and external pudic veins. A dense capillary network sur- 
rounds the alveoli and milk ducts. The venous system is so extensively 
developed in the teats that these organs are to be classed with erectile 
structures. The connective tissue carries numerous lymph vessels 
which surround the alveoli and blood vessels or lie free in the inter- 
lobular tissue, and empty into the supramammary lymph glands. The 
nerves of the udder arise from the lumbar plexus, and the terminal 
fibrillse form an extensive network but are without end-organs. 

Physiology of milk secretion. — As has been abundantly demon- 
strated milk can not be considered as a simple transudation from the 
biood. Lactalbumin differs from blood albumin. Casein and milk 
sugar are not found in the blood. The fat globules can not possibly be 



derived from the blood, and potash salts predominate in the milk as 
contrasted with soda salts in the blood. Bauber proposed the hypothe- 
sis that the leucocytes become metamorphosed and disintegrated to 
form the constituents of milk. The leucocytes, however, are never 
present in sufficient numbers to account for the quantity of milk se- 
creted, and their protoplasm does not contain chemicals which could be 
modified into the constituents of milk. Milk may properly be consid- 
ered as the result of liquefaction and fatty degeneration of the mam- 
mary parenchymatous cells or parts of these cells. As well stated by 
Tiievel, milk secretion is a specific function of the mammary gland. 
The chemical bodies which are brought to the gland in the blood are 
here modified into the constituents of milk and discharged into the 
lumen of the alveoli. 

With regard to the individual elements of milk the water is derived 
directly from the blood. In the process of transudation this water 
carries the traces of urea, creatinin and xanthin which are normally 
found in the milk.. 

Casein is found nowhere else in the body, but is formed in the udder 
from the circulating protein furnished by the blood. The transforma- 
tion takes place in the gland cells. Von Behring, on the other hand, 
maintains that under the influence of metabolic products in the gland 
ceils the proteid bodies in the blood are modified into casein. Ac- 
cording to Basch and others casein is formed by a combination of 
nucleic acid from the epithelial cell and the blood serum in the glandu- 
lar alveoli. 

Milk sugar rarely occurs elsewhere than in milk. The exact steps 
by which it is formed are not known. That it may be formed from 
proteid bodies is apparent from the fact that dogs kept on an exclusive 
ration of meat yield a milk with a relatively high content of sugar. 
In the case of herbivora like cows the ration contains abundant ma- 
terial which can readily be transformed into milk sugar. It is well 
known that the animal body has the power to produce one sugar from 
another by transformation. Milk sugar may therefore be derived from 
grape sugar. 

A histological examination of the active mammary gland will show 
that the fat globules of milk come from the gland cells. Milk fat does 
not arise exclusively from the proteids of the secreting cells. Some of 
it must be derived from the body fat and also from the food fat. Ex- 
periments have shown that food fat may pass over into the milk, but 
m the udder it undergoes a transformation so that its original charac- 
teristics are lost. The iodine numder of body fat is different from 
that of milk fat. They are, therefore, distinct kinds of fat. The fat 
in colostrum, however, and that in the body tissues seem to be identical 
According to the extensive investigations of Arnold it appears prob- 
able that the secretion of milk fat depends upon modification of the 
cytoplasm of the mammary epithelial cells without disintegration of 



8 

the cells. Eat globules first appear at certain points in the basal por- 
tion of the cells near the nucleus. Later secretory vacuoles are formed. 
Arnold argues that milk fat arises as a synthetic product in the secre- 
tory cells of the udder. 

The mineral matters which make up the ash of milk are evidently 
derived partly from the blood and partly from the disintegration of 
the epithelial cells. The relative proportions in which these minerals 
exist in the blood are not the same as observed in the milk. 

The secretion of milk is to a striking degree under the control of 
the nervous system. The nervous state of the cow has an influence 
upon both the quantity and quality of the milk. Manipulation of the 
teats by the hands or by the calves in sucking sets up a nervous reflex 
which greatly stimulates the flow of milk. Nervous centers of milk 
secretion have been found in the brain. 

Bacteria in milk. — The bacteriology of milk is discussed in chapter 
XII. In this connection we may, however, refer to the bacterial con- 
tent of normal milk. When first secreted in the udder of the healthy 
cow milk is free from bacteria. In the milk ducts or milk cisterns the 
milk becomes contaminated with the bacteria which have penetrated 
from the outside. The nature and extent of this contamination de- 
pends upon the circumstances of each case. Most bacteria find in milk 
ideal conditions for their growth. They multiply rapidly and soon 
produce souring or other changes after which the milk must be con- 
sidered abnormal for consumption in a fresh state. Since it is impos- 
sible to obtain commercial milk free from bacteria it becomes necessary 
to set up legal standards for the bacterial content of milk. These 
standards vary in different States and are discussed below in this 
chapter. In respect of bacterial content the distinction between normal 
and abnormal milk is somewhat arbitrary, but for practical and sani- 
tary purposes the distinction has to be drawn. For a discussion of the 
kinds of bacteria in milk and of their action on milk consult Chapter 
XII. 

Enzymes in milk. — A number of enzymes or unorganized fer- 
ments have been found in milk. Stoklasa isolated an enzyme which 
ferments lactose, decomposing it into carbon dioxide, lactic acid, 
a icohol and acetic acid. Both aerobic and anaerobic oxydases occur in 
milk serum without being associated with any of the essential ele- 
ments. Spolverini found that when an oxydizing ferment was added 
to the ration the amount of the oxydase was increased in the milk. 
Experiments with amylase and certain other oxydizing ferments 
indicate that they do not pass over into the milk. Gillet found a 
lipase in milk which caused the decomposition of monobutyrin. The 
action of the lipase was not increased by the presence of bacteria in 
milk, but was destroyed by a high degree of acidity. The addition of 
sodium fluoride or chloroform diminished, but did not prevent the 



9 

action of the ferment. Since this lipase has no action on other 
glycerids than monobutyrin it was called monobutyrinase. It resists 
temperatures of 60°-65°C. 

Lesperance reports the presence of peptic, tryptic, lipasic and glyco- 
lytic ferments in milk. According to Seligmann there are at least 
three oxydizing ferments in milk. Superoxydase, corresponding to 
the catalase of Loew, decomposes hydrogen peroxide and may be pre- 
cipitated with casein by means of an acid. A direct oxydase is also 
found not requiring the presence of hydrogen peroxide to produce a 
reaction. Finally milk contains indirect oxydases which are active 
only in the presence of hydrogen peroxide. The power of milk to de- 
compose hydrogen peroxide is increased by the additions of formalin, 
3S is also the power to give color reactions for enzymes. Raw milk 
loses its power of reaction by heating, while the milk treated with 
formalin is only slightly changed in this respect. Boiled milk showing 
no reaction is again rendered active by treatment with formalin. Var- 
ious tests used for distinguishing raw and boiled milk lose their value 
since formalin can restore the reaction lost by heating. 

By means of hydrogen peroxide milk may be sterilized without 
destroying the enzymes present in it. In this way a proteolytic 
enzyme has been discovered, its action being increased by adding 
alkali and raising the temperature. The proteolytic action of hydro- 
gen peroxide may easily be distinguished from that of the enzyme. 
According to some investigators amylolytic enzymes are much more 
frequently found in milk than are proteolytic enzymes. 

Galactase, a proteolytic enzyme of milk has been studied by Bab- 
cock, Russell and others. This enzyme is more active in colostrum 
than in normal milk. The progressive formation of soluble nitrogen- 
ous compounds is very striking as milk increases in age. Galactase 
attaches itself to finely divided particles in suspension. It therefore 
occurs in larger proportions in cream and separator slime than in milk. 
Concentrated extracts of galactase prepared from separator slime 
rapidly oxidize hydrogen peroxide. Galactase is destroyed by heating 
for 10 minutes at 76°C, or by mercuric chloride, formalin, phenol or 
carbon bisulphide. The decomposition products formed by galactase 
are very similar to those of tryptic digestion. Galactase added to 
milk first coagulates the casein and afterwards redissolves the curd. 
Babcock and Russell have shown that the main proteolytic changes 
which take place in the ripening of certain cheeses are due to the action 
of galactase. The presence of lactic acid diminishes the action of ga- 
lactase. 

Leucocytes in milk. — Leucocytes collect in the connective tissue of 
the active mammary gland and find their way into the milk. They 
are always to be found but their numbers vary greatly. Some confusion 
has been caused by attempts to distinguish arbitrarily between leuco- 



10 

cvtes and pus cells. Stokes, Bergey and others have been inclined to set 
up the arbitrary standard for normal milk of 10 leucocytes for one field 
of a 1-12 immersion lens. More than this number are considered as 
constituting pus. A number less than ten per field of the microscope 
is held to be the normal leucocyte count. On the basis of numerous 
tests Barthel came to the conclusion that milk normally contains great 
numbers of leucocytes. The reaction with peroxide of hydrogen is 
attributed to their presence. Cream and separator slime are richer in 
leucocytes than skim milk, on account of the fact that the leucocytes 
adhere to the fat globules or other finely divided particles, Barthel 
considers the leucocytes or an enzyme secreted by them as the cause 
of the phenomenon observed by Babcock and Russell and by them at- 
tributed to galactase. 

According to the method of Stewart a diseased condition of the 
udder is to be suspected if the milk contains more than 100,000 leu- 
cocytes per cc. The Doane-Buckley method, however, gives much 
higher counts than the Stewart method. Ward in testing these methods 
came to the conclusion that the Doane-Buckley method is the more 
reliable, and that it is not possible to detect udder disease in cows by 
the examination of mixed milk for number of leucocytes alone. Ward 
also insists that the presence of streptococci in milk can not be con- 
sidered as proof of mammitis, and that the microscopic examination 
of milk for staphylococci is of doubtful value. An average count of 
49,000 leucocytes per cc. was obtained from healthy cows; in one 
dairy the count was 191,000 per cc. In another dairy one cow showed 
a count of 4,800,000 per cc. Russell and Hoffman found wide vari- 
ation in the leucocyte count of cows showing no disease of the udder. 
These investigators believe that not enough data have been accumulated 
to formulate a scientific standard for judging milk for the presence of 
pus. In healthy cows the number of leucocytes ranged between 50,000 
and 1,000,000 per cc. At present it seems impossible to distinguish 
between pus cells and leucocytes, and the role and significance of leu- 
cocytes in milk need further study. 

Germicidal substances in milk. — Several investigators, notably 
Honing, Hunziker and Meyer, maintain that milk possesses certain 
bactericidal properties. It has frequently been observed that for some 
time after being drawn milk shows a diminution in the number of 
bacteria which it contains. This apparent bactericidal power of milk 
is more pronounced a t relatively high than at low temperatures. 
Koning claims that he has observed a difference in the bactericidal 
power of the milk of different cows. Colostrom in some instances seems 
to exercise a strong bactericidal influence. The supposed germicidal 
action of milk affects both milk bacteria and also various pathogenic 
bacteria. The soluble proteids of milk such as lactalbumin and lacto- 
globulin possess no bactericidal action toward coli or typhoid bacilli. 

Conn and Stocking do not believe that the decrease frequently ob- 



11 

served in the total number of bacteria in milk during the first few 
hours after milking is due to a germicidal action possessed by the milk, 
but believe that certain species of bacteria finding milk an unsuitable 
medium for growth, disappear more or less rapidly, and that when 
such species are more numerous than those finding milk a suitable 
medium a decrease in the total number of bacteria may result. Lactic 
acid bacteria multiply continuously from the outset. Their growth 
produces an acid reaction in the milk in the presence of which many 
other species of bacteria can not grow. 

The possible passage of specific antitoxic and immunizing bodies 
from the cow into the milk has been actively discussed in recent years. 
Opinions are still far apart on this problem. Some investigators like 
von Behring have argued that the milk of cows affected with disease 
carries the specific antibodies of the disease and therefore has the 
effect of immunizing calves or human beings which may drink the 
milk. The extent to which milk may carry immunizing properties 
is still an open question. 

Physical Properties of Milk. 

Color. — llilk is nearly white. In different animals it varies from 
semitransparent to completely opaque, especially in thick layers. 
When viewed in thin layers it has a bluish tint. Neither the white 
nor the blue color is due to a pigment. The blue color is a sort of 
fluorescence, while the white color is caused by the fact that milk is 
not a homogeneous fluid but is composed of substances of different re- 
fractive indices. The small innumerable fat globules reflect the rays 
o.t light in various directions, and few if any of the rays of light pene- 
trate through the milk. The smaller the number of fat globules in 
the milk the less opaque the sample. The yellowish tint frequently 
observed in milk is apparently derived from the feed stuffs. 

Specific gravity. — In order to detect the possible dilution of milk 
the specific gravity is determined. In normal milk the average spe- 
cific gravity is 1.030 at 60°F. and 1.029 at 70°F. If the lactometer 
spindle floats above 33 it may be assumed that the milk has been 
skimmed, and if it floats below 29 that it has probably been watered. 
The specific gravity of normal milk may vary from 1.028 to 1.035 ; 
m individual cows it may occasionally sink as low as 1.026, or rise as 
high as 1.038. In mixed or herd milk the variation is much less. 
The usual variation in herd milk is from 1.030 to 1.033. The lacto- 
meter indicates the specific gravity of milk at a temperature of 60 °F. 
Corrections must be made for other temperatures. 

Viscosity. — Viscosity is a term used to denote cohesion or friction 
between the particles of a fluid. It is determined by noting the time 
required for a given quantity of the fluid to flow through a tube of 
known size. The viscosity of milk or cream is greater than that of a 



12 

homogeneous liquid of the same specific gravity. The larger the fat 
globules in a sample the greater the viscosity. The viscosity decreases 
as the temperature of the milk increases. Thus at the freezing point 
Uie viscosity of milk is two times greater than water, while at 30° C. 
il is only 1.7 times greater. A number of viscometers have been 
devised which are well adapted to determining the viscosity of milk 
and cream. 

Odor. — The odor of milk often resembles that of the cow's skin, but 
such is not the case if proper cleanliness has been observed in milking. 
Milk has a characteristic, indefinable odor apparently depending upon 
an odiferous body of unknown composition. Aromatic substances 
sprayed on the cows to keep off flies may lend an odor to the milk. 
Various drugs and medicines have the same effect. The specific odor 
of the feeding stuffs used in any particular case is very apparent. Some 
of these odors are objectionable, while others are barely perceptible 
and not disgusting. Distillery byproducts, rape, onions, cabbage, 
lurnips and silage may be mentioned among such substances. 

Microscopic appearance. — Under the microscope the fat globules are 
the most conspicuous elements of milk. They vary in size from almost 
tne limit of visibility to .0309 mm. The largest fat globules have 
been observed in sheep milk. In cows a variation in size is to be noted 
in different breeds. The fat globules are small in Holsteins, medium- 
sized in Brown Swiss and large in Shorthorn and Jersey. At the 
beginning of lactation the globules are largest and gradually become 
smaller toward the close of the period. Well in comparing these con- 
ditions at the beginning and end of lactation found the ratio of fat 
globules per cmm. to be 103 :213, and the ratio of size 458 :170. The 
morning milk has larger fat globules than the evening milk, and in the 
first streams both the number and size of the fat globules are smaller. 
In an ordinary sample of milk the largest fat globules are about six 
times the size of the smallest. There seems to be some relation be- 
tween the globules of different size. Aikman suggests that the weight 
of the small globules probably equals that of the large ones. 

If leucocytes are present in milk they appear as relatively large 
cells with nucleus. Several kinds of leucocytes may be recognized. 
Lymphocytes are small cells with a deeply staining nucleus. Large 
uninuclear leucocytes are larger with a larger, less deeply staining 
nucleus and a larger mass of protoplasm. Multinuclear cells show 
an irregular nucleus or several nuclei or nuclear granules. 

Specific heat of milk. — Since milk varies in composition its specific 
heat varies accordingly. According to Fleischmann's determinations 
the specific heat of milk averages .874 and of cream .78. Gruerin 
found the specific heat to be .98, and Schnorf found it to range from 
1.004 to 1.085 with an average of 1.042. If the last determination be 
correct it is apparent that more refrigeration is required in freezing 
milk than in freezing water. 



13 

Freezing point of milk. — It has been found that the freezing point 
of milk lies .54°-.58°C. under that of water. If water is added the 
freezing point approaches that of water. The cryoscopic test may 
therefore be used in detecting dilution with water. In tuberculosis, 
mammitis and various other diseases the freezing point of milk is 
lowered. 

Density of milk. — The maximum density of milk appears at a tem- 
perature of — .3°C as compared with 4°C. in the case of water. The 
expansion coefficient of milk increases with the temperature and also 
with the increase in solid contents. 

Refractive index of milk. — The refractive power of milk varies 
greatly according to the composition. In normal milk the refractive 
index ranges from 1.3470 to 1.3515. A minimum of 1.3435 is very 
rarely observed. 

Cohesive power of milk. — At a temperature of 5°C. the cohesion of 
milk is 100.15 with water at 100.. At higher temperatures, however, 
the cohesive power of milk is less than that of water. 

Electrical resistance and conductivity. — The electrical conductivity 
of milk depends upon the degree of dissociation of the salts which it 
carries in solution. The resisting power of milk ranges between 180 
and 210 ohms. If water is added to milk its resistance is increased. 
An accurate determination of the amount of dilution can not be made 
bv an electrical test for the reason that the resisting power of water 
varies with its salt content. 

Basis of the methods of creaming milk. — The fat globules are 
lighter than the milk serum. Consequently the fat is separated by the 
force of gravity or centrifugal motion. Several methods of separation 
axe in common use. In the shallow pan system the milk is poured 
into pans to a depth of 2-4 inches and kept at a temperature of 40°- 
G0°F. for 36 hours at the end of which time the cream is as nearly 
separated as may be by this system. From .5 to 1 per cent of the 
cream remains in the milk serum. This is due to the fact that some 
of the fat globules are caught and held by the curdling casein, fibrin 
or other constituents of the milk. Obviously any fat which is caught 
in the curd can not rise to the surface. Deep setting consists in placing 
the milk in Cooley or shotgun cans about 8 inches in diameter and 20 
inches deep. If the milk is kept at a temperature of 40 °F. it does 
not curdle so rapidly and the cream rises somewhat more quickly, the 
process being completed at the end of about 24 hours. When properly 
operated only about .2 per cent of the cream is lost by this system. 
The physical basis of the dilution method is the fact that the whole 
mixture possesses a lower viscosity than undiluted milk and that 
therefore less resistance will be offered to the rising; fat srlobules. If 
milk is diluted with an equal quantity of pure cold water the fat will 



14 

rise in a few hours after which the water and milk serum may be 
drawn off from below, leaving the cream. 

The centrifugal separator depends for its efficiency upon the same 
fact as that utilized in separation of cream by gravity, viz. that fat 
globules are lighter than milk serum. When milk is revolved at high 
velocity in the bowl of a separator the fat globules remain near the 
center of the column while the serum and other constituents of the 
milk are thrown to the outside. The cream and skim milk may there- 
fore be removed by separate tubes in continuous streams. The various 
makes of separators differ chiefly in the diameter of the bowl, rate of 
revolution and the fixtures in the bowl. The essential principle, how- 
ever, is the same in all. 

Chemistry of Milk. 

Reaction. — The milk of carnivorous animals has an acid reaction. 
In herbivora the reaction varies being sometimes neutral, sometimes 
alkaline, sometimes slightly acid and usually amphoteric. Milk with 
an amphoteric reaction turns blue litmus paper red and red, paper 
blue. According to Soxhlet the amphoteric reaction is due to the 
presence of two sodium salts of phosphoric acid, one of which is acid 
and the other alkaline. The exact nature of the amphoteric reaction is 
not well understood and it has little significance. With some testing 
papers and coloring matters milk always shows an acid reaction while 
with other tests the reaction is uniformly alkaline. In most cases the 
apparent reaction is as much a function of the testing substance as of 
the milk. The reaction of normal milk, however, is always nearly 
neutral, being only slightly acid or alkaline. Fresh milk tastes sweet 
on account of its content of lactose. The lactose is soon broken up 
into lactic acid, and other compounds by the action of lactic acid bac- 
teria after which the reaction is decidedly acid. 

Composition — Milk has a very complex composition. The chief 
constituents of milk are water, fat, milk sugar, casein, lactalbumin, 
lecithin, cholesterin, citric acid, extractives, salts and gases. Of 
these water, fat, proteids, milk sugar and salts are most important. 
Analyses have been compiled showing the content of these substances 
in milk from mixed and pure herds in various countries. These 
analyses vary in certain details as is to be expected in a fluid, subject 
to such variations as milk. In general it may be said that milk con- 
tains 87 per cent water and 13 per cent solids. An average deduced 
from 200,000 analyses indicates water 87.10 per cent, fat 4 per cent, 
milk sugar 4.75 per cent, casein 3 per cent, albumin .4 per cent and 
ash .75 per cent. The fat may vary from 1 per cent to 12.5 per cent, 
and the solids not fat from 5 per cent to 10.6 per cent. 

Fat. — Milk fat is in a finely divided state and of better flavor than 
other fats. Like all fats it is made of glycerids composed of glycerine 



15 

and a fatty acid. The most important glycerids in milk fat are 
stearin, palmitin and olein, but there are several others such as butin, 
butyrin, caproin, caprylin, caprin, laurin and myristin. Stearin 
melts at 55°C, palmitin at 62.8°C, and myristin at 31°C. Most 
of the other fats are liquid at ordinary temperatures. The aver- 
age composition of milk fat is butyrin 3.85 per cent, caproin 
3.6, caprylin .55, caprin 1.9, laurin 7.4, myristin 20.2, palmitin 
27.7, stearin 1.8, and olein 35 per cent. The proportions of 
these glycerids vary considerably and the melting point ,of 
milk fat is therefore variable, ranging from 29.5° to 33°C. Milk 
fat. is soluble in water and also non-volatile. The density of milk fat 
ranges from .9307 at 15°C. to .8667 at 100°C, and the specific grav- 
ity ranges, from .9300 at 15°C. to .8637 at 100°C. The average index 
of refraction is 1.4566. According to Richmond milk fat mixes with 
esters, is dissolved by glycerol, all hydrocarbons which are liquid at 
ordinary temperatures, ether, carbon bisulphide, nitro-benzene, and 
acetone. Butter fat becomes rancid as a result of hydrolvsis, split- 
ting: up into fatty acids and glycerol. The latter is oxydized, yielding 
aldehydes and soluble acids. The fact that the globules of milk fat do 
not coalesce but remain separate has caused much speculation. Storch 
has proposed the theory that each globule is surrounded by a mem- 
brane of casein or mucoid material. The chemical study of milk has 
furnished little evidence in favor of this theory and it seems unneces- 
sarv to explain the emulsified condition of milk. 

Casein. — Casein, or as some writers prefer to call it caseinogen, is 
the chief albuminoid of milk. Other albuminoids described as occur- 
ing in milk are lactalbumin, lactoglobulin, galactin, galactozymase, 
syntonin, albumoses, fibrin, nuclein, galaetase, etc. Casein is found in 
milk in a fluid condition but is not soluble in water. Sulphur is in- 
corporated in the molecules of casein which, therefore, belongs with 
rhe nucleins. According to Kirchner the percentage composition of 
casein is carbon 53, hydrogen 7.12, nitrogen 15.65, oxygen 22.6, 
sulphur .78, phosphorus .85. Pure casein is a white, amorphous, 
tasteless, odorless body, practically insoluble in water, completely in- 
soluble in alcohol or ether, slightly soluble in acids and readily soluble 
m alkaline solutions. Tf casein comes in contact with lime it takes up 
some of it and therefore often contains lime to the extent of 1 per 
cent. In fresh milk casein is in a colloidal or semidissolved state and 
is somewhat opaque. If milk is allowed to stand a small portion of 
the casein is changed into soluble peptones. The curd of milk is com- 
posed chiefly of casein which may be coagulated by acids (such as 
lactic in souring milk) , rennet enzyme, trypsine and certain other fer- 
ments. 

Lactalbumin. — In normal milk lactalbumin differs from blood al- 
bumin but in colostrum it is nearly identical with the latter. The 
average amount of lactalbumin in normal milk is .6 per cent but in 



16 

colostrum it is much more abundant. Lactalbumin is soluble in water 
and is not coagulated by rennet or dilute acids. It is coagulated, how- 
ever, by a temperature of 70-75 °C. Moreover, it is precipitated by 
alcohol, phosphotungstic acid or tannin. Its composition is not 
changed by coagulation. Lactalbumin contains no phosphorus but 
contains more sulphur than does casein. 

Laetoglobulin. — This albuminoid is readily soluble in sodium chlo- 
ride solutions, is coagulated by heat and precipitated by tannin or 
neutral sulphates. In colostrum it may be present to the amount of 
8 per cent but in normal milk there is merely a trace. It appears to 
be identical with serum globulin. 

Galactin or lactoprotein. — This peptone is present in fresh milk to 
the extent of .13 per cent. According to Richmond galactin is com- 
posed of portions of the casein and lactalbumin and their decomposi* 
tion products. 

Other albuminoids. — Galactalzymase, syntonin, albumoses and pep- 
tones exist in milk at most in mere traces, and are perhaps not normal 
constituents but rather decomposition products. Babcock claims to 
have demonstrated fibrin in milk with a coagulation power one two 
thousandth part that of blood fibrin. Milk is said to give the guaiac 
and H 3 O 3 test for fibrin. True peptones are apparently not present 
in normal milk. Nucleon or sarcophosphoric acid was found in milk 
by Siegfried in the proportion of .09 gm. per liter. The mucoid pro- 
leid described by Storch is probably a modified portion of the casein. 

Milk sugar. — Milk sugar or lactose is found only in milk. Its 
composition isG 12 U 2Y 11 -U 2 0. Under the influence of lactic acid 
bacteria each molecule of milk sugar breaks up into four molecules of 
lactic acid. It contains one part of water of crystallization which is 
not driven off by drying the sugar at a temperature of 100° C. It 
does not readily dissolve in water or alcohol and is therefore not very 
sweet. At a temperature of 15 °C. about 7.5 gm. is dissolved in 100 cc. 
ot water. Milk sugar dissolves the oxides of lime, lead, copper and 
mercury. It is not fermented by trypsin, pepsin, rennet, yeast, inver- 
tase, or diasase. It is hydrolized into glucose and galactose, however, 
by lactase which is found in kephir grains. In commercial practice 
milk sugar is obtained by crystallization after the fat and albuminoids 
have been removed. The preparation of milk sugar is therefore most 
profitably combined with the cheese industry. 

Mineral constituents. — The ash obtained by burning milk does not 
truly represent the mineral elements in milk, some of them being 
thereby changed. While present in small proportion the mineral 
constituents of milk are very important. They vary in amount less 
than the other constituents of milk. On an average the ash constitutes 
aDout .75 per cent of the milk, varying from .5 to .9 per cent. Soldner 
gives the following composition of the ash of milk: 



17 

Sodium chloride 10.62 

Potassium chloride 9.16 

Monopotassium phosphate 12.77 

Dipotassium phosphate 9.22 

Potassium citrate 5.47 

Dimagnesium phosphate 3.71 

Magnesium citrate 4.05 

Dicalcium phosphate 7.42 

Tricalcium phosphate 8.90 

Calcium citrate 23.55 

Lime combined with proteids 5.13 

While, however, the total amount of mineral matter in milk varies 
within very narrow limits the individual mineral constituents vary 
greatly in amount. Citric acid and lime may be considered as normal 
constituents of milk. In some samples of milk sulphur has been found 
to the extent of .043 per cent. Occasionally iron is found in the milk 
of cows, goats and women. It is commonly believed that a portion of 
the phosphorus in milk is in organic union with nuclein and lecithin. 
Other substances sometimes found in normal milk include acetates, 
silica, iodine, fluorine, thio-cyanates, amyloid, urea, alcohol, lactic 
acid, acetic acid, leucin, cholesterin, creatin, xanthin, ty rosin, a color- 
ing matter, an odoriferous substance, oxygen, nitrogen, carbon dioxide 
and other gases. Recently Biscaro isolated potassium orotate from 
milk sugar. The enzymes commonly found in milk have been men- 
tioned in discussing its biology. 

Factors Influencing the Composition of Miek. 

Breed. — The influence of the breed of cow upon the composition of 
the milk has received a great deal of attention. The results obtained 
in this study are by no means uniform. There is the greatest varia- 
tion in respect of composition of milk within the same breed. In 
general, however, the Guernseys and Jerseys give milk relatively rich 
in fat, and the Holsteins and Dutch Belted a milk relatively low in 
fat content. The other breeds stand somewhat intermediate in this 
respect. In milk tests of breeds attention is chiefly directed to the fat 
content of the milk. The total solids vary less than the fat, In a 
test by Lloyd the fat content of the milk was 3.74 per cent in Short- 
horns, 5.38 in Jerseys, 5.01 in Guernseys, 3.65 in Red Polls. 4.33 in 
Kerries and 3.97 in crosses. In the same test the total solids were 
highest in Jerseys and lowest in Shorthorns. In a test in Wisconsin 
the milk yield was highest in Holsteins followed by Brown Swiss, 
Shorthorn, Guernsey, Ayrshire, Dutch Belted, French Canadian, Red 
Polled, Jersey, Polled Jersey and Devon. 

In a test of fat percentage the Jersey stood at the head followed by 
Guernsey, Polled Jersey, Devon, French Canadian, Ayrshire, Red 
Polled and Shorthorn. A comparative test in Toronto placed the 



18 

breeds in the order Aberdeen Angus, Hereford, Shorthorn, Ayrshire. 
In a test in New York the Guernsey stood at the head followed by 
Jersey, Ayrshire, Shorthorn and Holstein. It is apparent from these 
few figures that the breed is not as important as the individual merit 
of the cow. 

Age of cow. — In Algau it has been found that the yield and fat 
content of 'milk increase up to the fifth calving after which both de- 
crease. The results of extended observations in Scotland covering 
1,340 cows indicate that in mixed herds cows 15 years old give milk 
with a fat content of 3.74 per cent, and cows two years old 3.83 per 
cent. This difference is not striking. ~No regular increase or decrease 
was found in cows of ages intermediate between two and 15 years. 
A series of milk records kept for five years shows that young cows 
give milk richer in fat, while older cows give more milk. It may be 
safely asserted that any individual cow yields as rich milk as a heifer 
as she will as a mature cow. 

Period of lactation. — At the beginning of lactation the amount of 
milk is high and the fat content low. During the first few days the 
milk is known as colostrum and has a very different composition from 
normal milk. The composition of colostrum is about as follows: 
albumen 6.77 per cent, fat 3.57, sugar 4.68, mineral salts -82 and water 
84.16 per cent. The solids of colostrum may be as high as 20 per 
cent. In the course of the period of lactation the yield gradually 
diminishes while the fat content rises. After a few weeks the fat 
content may fall slowly till near the end of the period of lactation 
when the fat content becomes abnormally high and the yield very 
low. Just before the cow is dried off the fat percentage may be so 
high as to render the milk almost abnormal. The percentage of the 
other solids is not affected. The ash. content of the milk remains 
practically constant during the whole period of lactation. Variation 
is greatest in the fat and less in the milk sugar and proteids. An in- 
crease or decrease in the fat content is usually accompanied by an 
opposite change in the content of protein and milk sugar. Dividing 
the period of lactation into three equal parts the sugar is 10-12 per cent 
greater during the first months of the second period than in the 
first period, but later it slowly diminishes. The total amount of fat 
and casein of the second period follows closely the milk yield. Van 
ISlyke found the per cent of fat highest during the first month of lacta- 
tion. In the second month it dropped considerably in the richest 
milk. The total yield of milk increases, however, so that the greatest 
fat yield is obtained during the second and third months. As the 
period of lactation progresses there is more and more fat lost in the 
skim milk. In some cases this loss of fat is not observed. 

Individuality. — The greatest differences are observed in the fat 
content of the milk of individual cows of the same breed. Thus 
Heischmann in a continued study of this point in 18 cows of the same 



19 

breeding and subjected to the same conditions found that the fat con- 
tent of the milk varied from 2.66 per cent to 3.88 per cent, Wherever 
this matter has been investigated it has been found that the individual 
peculiarities of the cow are of the highest importance in determining 
the fat content of the milk. The fat in the milk of one cow may be 
very high while in another it may be low with no assignable reason 
except the individual nature of the cows concerned. The tendency to 
produce milk of a high fat content is in a pronounced degree heredi- 
tary. The tendency is not always inherited from the mother but a 
bull with an excellent milking ancestry is of great influence in in- 
creasing the fat content of the milk of his offspring as compared with 
the grade cows to which he is bred. 

Manner and time of milking. — During the course of each milking 
there is an increase in the fat content. By separating one milking 
into 17 portions Shov found that the fat content increased from .7 to 
8.9 per cent, or in one case to 9.6 per cent, Four characteristic 
periods were observed in the same milking. In the first the milk con- 
tained less than 1 per cent of fat, in the second period there is a sudden 
rise of fat content, in the third period the fat remains at the high 
point, while in the last sample there is a great increase in the fat. In 
certain cow t s extremes of .8 and 13 per cent were observed. 

Differences have been observed in the fat content of morning's and 
evening's milk. Fleischmann in a long series of tests found a. fat con- 
tent of 3.26 per cent in morning's milk and 3.18 in evening's milk as 
compared with 3.22 for the day. In other investigations, however, 
the content of fat, protein and ash has been higher in the evening and 
the content of milk sugar lower. Gilchrist found the morning's milk 
sometimes below the market standard in fat and recommends three 
milkings per day to prevent this occurrence. Beach found that by 
milking three times a. day the total yield of fat was increased 14 per 
cent, Slight inequalities in the intervals between milking cause no ser- 
ious effeft upon the quality of the milk so long as the changes are not 
sudden. Great inequalities in the intervals may reduce the fat per- 
centage. A change from a narrow to a wide ration is likely to diminish 
the fat content of the morning's milk more than that of the evening. If 
ail the grain is fed in the evening the fat content of the morning's milk 
is increased in most but not all cases. If the intervals between milkings 
are very unequal the larger milk yield and lower fat percentage follow 
the longer interval. Stokes believes that cows reassimilate some of the 
fat for their own uses if the milk is allowed to remain too long in the 
udder. In one test of three milkings per day the fat percentage was 
highest at noon and lowest in the morning. An experiment in milk- 
ing cows four times per day showed that the yield of fat is thereby 
increased but the percentage diminished. The advantages of milking 
more than two times per day are not sufficient to justify the procedure. 

The foremilk is not rich in fat and has a high bacterial content. 



20 

"From 4 to 10 streams should therefore be discarded. The strippings 
contain the highest fat percentage. Much fat is therefore lost if the 
cows are not thoroughly stripped. The efficiency of milkers differs 
greatly in this respect. The Hegelund method of milking, described 
in Chapter VI, has been highly recommended by Woll for increasing 
the amount of fat obtained. The composition of the aftermilk ob- 
tained by the Hegelund method is essentially the same as that of the 
ordinary strippings. 

Lepoutre found that when each quarter of the udder was milked 
separately the fat percentage was highest in the first quarter milked, 
and lowest in the last quarter. If two quarters were milked simul- 
taneously the fat content of this milk was higher than that of the 
milk from the other two quarters. Ingle found appreciable but not 
constant differences in the composition of the milk from different 
quarters of the udder. Carlyle reports that a constant change of 
milkers so long as none of them is a stranger to the cows results in a 
slightly increased fat percentage. So far as milking machines have 
been tested they seem to have little or no effect upon the composition 
of the milk. 

Exercise, work, and fatigue. — In experiments carried out by Hills 
cows driven and transported by rail gave milk with a low fat content 
on the next day but for the following few days the fat content was 
above normal. The percentage of solids not fat was not affected. 
Morgan tried the experiment of working cows one or two hours daily. 
The percentage of fat was thereby increased while the content of milk 
sugar decreased greatly. A reasonable amount of exercise for the 
cows has little effect on the composition of the milk. 

Spaying. — If cows are spayed during a period of lactation this 
period may be extended for a year or two beyond the usual term. The 
milk yield gradually diminishes and its composition varies. As a 
rule the percentage of fat, milk sugar and casein is increased. Spaying 
may cause great temporary fluctuations in the composition of the milk 
after which it returns to its normal character. 

Estrum. — Milk may or may not show alterations in composition 
during estrum. Malpeaux noted a slight diminution in fat. Snorf 
found that estrum had no effect on the electrical conductivity of milk 
but lowered the freezing point. The percentage of fat may be tem- 
porarily increased but soon falls to normal Doane made determina- 
tions of the total solids, fat, protein, casein and sugar in the milk of 5 
cows before, during and after the periods of heat. In no case was 
the percentage of fat lower than normal during the period of heat, 
and in only two instances was there any increase. No variations were 
observed in the other constituents nor in the temperature of the cows. 

Weather. — Sudden climatic changes and unpleasant weather are 
more likely to affect the amount than the composition of the milk. 
The Essex County council of England found no evidence that exces- 



21 

sively dry or wet seasons had any influence on the quality of milk. 
Stokes, however, traced some abnormal milk in London to farms where 
the cows were subjected to drouth and excessive heat. The total solids 
in the milk amounted to 12.6 per cent. Crowther found that extremes 
of temperature tend to cause a decrease in the fat content of milk. 
After studying this matter Dymond states : "Throughout this exper- 
iment the considerable variations in fat and solids have not been to 
any great extent due to alterations in food or weather or to any ex- 
ternal conditions under which the cows were kept and which the dairy 
farmer could control. The important point is to recognize that these 
changes are continually taking place but since they are not usually 
dependent on external conditions but on the idiosyncrasies of each 
cow, almost complete uniformity can be obtained by mixing the milk 
of a sufficient number of cows." 

Seasons. — There is little or no difference in seasons as to the qual- 
ity of the milk. Richmond found the lowest fat content in May and 
June and the highest in October and November. These differences 
may have been due to other factors and are not uniformly observed. 
Other things being equal there is little difference in the average qual- 
ity of the milk during a whole period of lactation whether the cow 
calves in the spring or fall. 

Disease. — In case of any serious disease the milk should be con- 
sidered unfit for food. The changes produced in milk by the various 
diseases are discussed in Chapters III and XII. 

Excitement. — Under the influence of worry, excitement or fright 
cows may give milk of a fluctuating quality. At times the fat con- 
tent is as low as 1.8 per cent, at other times as high as 7 per cent. The 
other solid constituents are less affected than the fat. 

Feed. — It has long been the dream of dairymen to devise a ration 
by means of which the fat content of the milk could be greatly in- 
creased. This achievement seems to be quite impossible. The results 
of hundreds of experiments along this line indicate that it is impossible 
to increase materially or permanently the fat yield of a cow by 
changes in the amount or character of the ration, except in so far as 
the increase in the total yield of milk increases simultaneously the total 
fat yield. The percentage of fat is not thereby affected. Woll found 
that "the food of the dairy cow influences the quality of the milk pro- 
duced to this extent that the cow will yield a maximum flow of milk of 
the highest fat content which she is capable of producing on rations rela- 
tively rich in nitrogenous substances." Wing and Foord experimented 
with a herd of cows which had been previously poorly fed and cared 
for. By feeding them an abundant ration easily digestible and rather 
nitrogenous in character and continued through two years an aver- 
age increase of .25 per cent of fat was obtained. This was accom- 
panied by an increase of about 50 per cent in the total amount of 
milk fat produced. With cows which have been well fed, however, a 



22 

change works no permanent effect on the quality of the milk. While 
it is impossible to increase the fat or other constituents of milk indefi- 
nitely or permanently, the ration nevertheless exercises appreciable 
effects upon the composition of the milk. Morgan demonstrated that 
to a certain extent food fat exerts an invariably favorable influence 
upon the production of milk fat, and that fat should not be omitted 
from the ration of dairy cows. A few instances of specific effects of 
rations upon the composition of the milk may be mentioned. In gen- 
eral the cows which consume the most food produce the most fat. In 
one case the discontinuance of silage caused a slight increase in the 
acidity of the milk. If calcium phosphate is added to a ration which 
already contains sufficient mineral matter for the ask of milk, an 
increase in the phosphate content of the ash is noted. Mayer found 
that butter made from cows which were fed 4 pounds of sugar per 
day had a low melting and solidifying point and the volatile fatty 
acids were increased. In many cases great changes in the mineral 
elements of the ration have caused no corresponding changes in the 
composition of the milk. 

Milk fat is derived from carbohydrates, fat and protein in the food 
and from body fat. The addition of large quantities of fat to the 
ration may cause a marked increase in the fat content of the milk for 
-a time or to a certain degree. Beyond this point it may produce the 
opposite effect. The use of the oils obtained from cottonseed, linseed, 
corn and various other feeds may have a temporarily good effect upon 
the fat content of the milk. At the same time the sugar and proteids 
as a rule remain without change. If a ration containing much oil is 
used the milk at first shows an increase in fat but soon returns to a 
normal condition. In rare cases the peculiar properties of the food 
fats can be recognized in the milk fat when the former were fed to 
excess. For the most part, however, the food fat loses its individuality 
in the mammary gland. A change from pasture to dry feed or vice 
versa may increase or decrease the fat percentage. Lindsey found 
that feeding corn oil reduced the saponification of the milk 10 points 
and the Reichert-Meissl number Sy 2 points, and raised the iodine 
number 9 points. The melting point of the milk fat was not changed. 
In experiments with sheep Gogitidse estimated that as much as 33 
percent of the constituents of linseed oil passed directly into the milk. 
The iodine number of the milk fat was rapidly increased but soon fell 
to the normal after the oil was omitted from the ration. 

Slight temporary effects are produced on the composition of milk 
bv almost any change in the ration. The essential oils or aromatic 
substances in the feed may be detected in the milk. The mineral con- 
stitution of the feed affects the ash of the milk. But these as well as 
the effects of other feeds mentioned above are temporary and non- 
cumulative. The best system of feeding consists in the use of a well 
balanced ration of medium ratio. 



23 

Freezing. — In freezing the solid constituents of the milk are forced 
out (with the exception of the fat) and the fluid portion contains more 
casein, sugar and ash than the ice milk. If a large can of milk is 
frozen into ice the upper layer contains almost all of the fat, while the 
central and lower portions contain most of the sugar and casein. The 
extent of the dissociation of the elements of milk in freezing depends 
upon the size of the vessel in which it is frozen. For a further account 
of the effect of freezing on milk see Chapter VIII. 

Shelter and care of cows. — In comparing stabling with turning out 
to pasture at night the higher fat percentage is sometimes obtained 
from the cows on pasture and sometimes from those in the stable. If 
cows are exposed to very cold weather the fat content may be lowered 
until the cows become accustomed to the change. Light and well ven- 
tilated stables are more favorable to the health of the cows than dark 
and poorly aired stables but within the limits of health the effect upon 
tiie composition of the milk is scarcely noticeable. Similarly changes 
in watering and grooming the cows appear to have no direct effect 
upon the quality of the milk. 

Dehorning. — In Arkansas dehorning cows in lactation produced no 
change in the composition of the milk. Lane also failed to note any 
change in the solids of the milk as a result of dehorning, but the yield 
was reduced. 

Size of the cows. — Linfield found no correlation between the weight 
of the cow and the composition of the milk. In Scotland small cows 
were found to give milk of a slightly higher average fat content than 
large cows. 

Gestation. — Most cows are pregnant during a large part of the 
period of lactation. The only observed effect of gestation upon the 
quality of the milk is a diminution of the phosphoric acid and lime 
up to the time of calving. 

Daily variation. — Variations are observed from day to day in the 
composition of the milk of individual cows. These variations are to be 
attributed to one or more of the factors mentioned above. The daily 
range of variation in total solids may be 2 or 3 per cent. In the herd 
milk of large dairies Siegfeld found the daily variation in the fat 
content to range from .1 to .3 per cent and not to exceed .45 per cent 
for the entire year. In terms of cubic centimeters of decinormal 
sodium hydroxide required to neutralize 100 cc. of milk the acidity 
may show differences of 1 or 2 cc. from day to day. The daily varia- 
tion in the fat content of the milk of individual cows is sometimes 
as high as 3 per cent. 

Mixing the milk. — In herd milk the daily variation in composition 
is very slight. This is due to the fact that the variation in different 
cows is not simultaneously in the same direction. The variations in 
the different cows therefore neutralize one another and the result is a 
uniform mixed milk. Radical variations in the composition of the 



24 

mixed milk of a herd "should be viewed with suspicion as indicating 
either mistakes in testing or gross mismanagement of the herd." 

Drugs. — As will be indicated in Chapter II various drugs and med- 
icines may affect the quality of the milk by lending their specific 
odors and flavors. Drugs are readily excreted with the milk. 

Method of drawing from the can. — Since the cream begins to rise 
as soon as the milk is drawn from the udder, it is necessary that the 
milk in a delivery can be stirred in order that the different portions 
removed at different times may have a uniform composition. Bitting 
found that the fat content of samples of milk drawn from the bottom 
of a can varied from 1 to 4.4 per cent, while dipped samples had a 
uniform composition. 

Legal Standards foe Normal Milk. 

In order that milk inspectors may have some basis upon which to 
oroceed in determining what are normal and what abnormal samples 
of milk it is necessary to establish legal standards. In the following 
table the standards adopted in the various states of this country are 
given : 

Total Solids 
Solids. Not Fat. Fat. 

United States 8.5 3.25 

California . • . 

Colorado • • • 

District of Columbia 9 3.5 

Georgia 8.5 3.5 

Hawaii 11.5 ... 2.5 

Idaho 8 3 

Illinois 12 ... 3 

Indiana 9 3 

Iowa 12.5 ... 3 

Kentucky 12 ... 3 

Maine 12 ... 3 

Maryland 12.5 ... 3.5 

Massachusetts 12-13 9-9.3 3-3.7 

Michigan 12.5 ... 3 Sp. Gr. 1.029-33 

Minnesota 13 ... 3.5 

Missouri 12 8.5 3.25 

Montana 12 9 3 

Nebraska • • • 3 

New Hampshire 13 9.5 3.5 

New Jersey 12 ... .... 

New York 12 ... 3 

North Carolina 12 8.5 3.25 

North Dakota 12 ... 3 

Ohio 12 ... 3 



25 

Total Solids 

Solids. Not Fat. Fat. 

Oregon 12 9 3.2 

Pennsylvania 12 ... 3 

Porto "Rico 12 ... 3 

Rhode island 12 ... 2.5 

South Carolina 8.5 3 

South Dakota 13 ... 3 

Utah 12.5 ... 3 

Vermont 12 8.5 3.25 

Washington 8 3 

Wisconsin 8.5 3 

Wyoming 11.5-12 ... 2.4 

These standards of composition are supposed to be applied to the 
mixed milk of a herd. If rigidly applied to the milk of a single cow 
it might be necessary to condemn the milk on certain days as below 
standard. 

Market Milk. 

One of the most important points to be considered with regard to 
market milk is its bacterial content. In actual samples of market milk 
taken in cities the bacterial content has been found to vary from a few 
hundred per cc. to 600,000,000 or even more per cc. It is an ex- 
ceedingly difficult matter to fix a standard for the bacterial content of 
milk. A standard once adopted has to be qualified in many ways. 
Pathogenic bacteria can not be tolerated in milk. Even the most harm- 
less lactic acid bacteria will sour the milk in a short time unless it is 
kept at a low temperature. A high bacterial content indicates unsani- 
tary conditions at the farm where the milk is produced, or careless- 
ness in handling and delivering the milk. Perhaps the best plan thus 
far suggested for the regulation of the bacterial content of market 
milk is that recommended by a milk conference in the District of 
Columbia. Three commercial grades or classes of milk are to be 
recognized as follows : 

Class 1. Certified milk. — The use of this term should be limited 
to milk produced at dairies subjected to periodic inspection and the 
products of which are subjected to frequent analyses. The cows 
producing such milk must be properly fed and watered, free from 
tuberculosis, as shown by the tuberculin test, and from all other 
communicable diseases, and from all diseases and conditions what- 
soever likely to deteriorate the milk. They are to be housed in clean 
stables, properly ventilated, and to be kept clean. All those who 
come in contact with the milk must exercise scrupulous cleanliness, 
and such persons must not harbor the germs of typhoid fever, 
tuberculosis, diphtheria, and other infections liable to be conveyed 
by the milk. Milk must be drawn under all precautions necessary 
to avoid infection, and be immediately strained and cooled, packed 
in sterilized bottles, and kept at a temperature not exceeding 50 °F. 
until delivered to the consumer. Pure water, as determined by chem- 
ical and bacteriological examination, is to be provided for use 
throughout the dairy farm and dairy. Certified milk should not 



26 

contain more than 10,000 bacteria per cubic centimeter, and should 
not be more than 12 hours old when delivered. Such milk shall be 
certified by the health officer of the District of Columbia. 

Class 2. Inspected milk. — This term should be limited to clean 
raw milk from healthy cows, as determined by the tuberculin test 
and physical examination by a qualified veterinary surgeon. The 
cows are to be fed, watered, housed, and milked under good condi 
tions, but not necessarily equal to the conditions provided for class 
1. All those who come in contact with the milk must exercise 
scrupulous cleanliness, and such persons must not harbor the germs 
of typhoid fever, tuberculosis, diphtheria, and other infections liable 
to be conveyed by the milk. This milk is to be delivered in steri- 
lized containers, and is to be kept at a temperature not exceeding 
50° P. until it reaches the consumer. It shall contain not more than 
100,000 bacteria per cubic centimeter. 

Class 3. .Pasteurized milk. — Milk from the dairies not able to com- 
ply with the requirements specified for the production of milk of 
classes 1 and 2 is to be pasteurized before being sold, and must be 
sold under the designation "pasteurized milk." Milk for pasteuriza- 
tion shall be kept at all times at a temperature not exceeding 60°F. 
while in transit from the dairy farm to the pasteurization plant, and 
milk after pasteurization shall be placed in sterilized containers and 
delivered to the consumer at a temperature not exceeding 50 °F. All 
milk of an unknown origin shall be placed in class 3 and subjected 
to clarification and pasteurization. No cow in any way unfit for the 
production of milk for use by man, as determined upon physical 
examination by an authorized veterinarian, and no cow suffering 
from a communicable disease, except as specified below, shall be 
permitted to remain on any dairy farm on which milk of class 3 
is produced, except that cows which upon physical examination do 
not. show physical signs of tuberculosis may be included in dairy 
herds supplying milk of this class, although they may have reacted 
to the tuberculin test. 

This milk is to be clarified and pasteurized at central pasteuriza- 
tion plants, which shall be under the personal supervision of an offi- 
cer or officers of the health department. These pasteurizing 
plants may be provided either by private enterprise or by the District 
Government, and shall be located within the city of Washington. 

By the term "pasteurization," as used herein, is meant the heating 
of milk to a temperature of 150 C F. or 65 °C. for 20 minutes, or 160°F. 
or 70"C. for 10 minutes, as soon as practicable after milking, in in- 
closed vessels, preferably the final containers, and after such heat- 
ing immediate cooling to a temperature not exceeding 50 °F. or 10 °C. 

No milk shall be regarded as pure and wholesome which, after 
standing for two hours or less, reveals a visible sediment at the 
bottom of the bottle. 

No dairy farm shall be permitted to supply milk of a higher class 
than the class for which its permit has been issued, and each dairy 
farm supplying milk of a specified class shall be separate and dis- 
tinct from any dairy farm of a different class; the same owner, how- 
ever, may supply different classes of milk, providing the dairy farms 
are separate and distinct, as above indicated." 

Other points are also to be considered in determining the standard 
of market milk. The variation in the number of leucocytes in milk 
will be discussed in Chapter II and XII. Apparently we are not yet 
in a position to set up a standard for the leucocyte count of milk. An 
analysis of 291 samples of market milk in Chicago showed that 25 per 
cent were below the legal standard of 3 per cent of fat and 30 per cent 



27 

were below the standard of 12 per cent of solids. Only 1.4 per cent 
of samples showed less than 50,000 bacteria, per cc. In various cities 
of Pennsylvania 18 per cent of milk samples were below standard in 
fat content, and 37 per cent of the samples showed less than 11 per 
cent of total solids. In market milk the common ratio of sugar, 
proteids and ash is 13 :9 :2. In Norway an analysis of about 15,000 
samples for each month of the year showed a variation in fat content 
of 3.3 to 3.6 per cent. The average fat content for 53,000 samples 
was 3.52 per cent, Richmond found rather more fat in milk from 
farms on cretaceous formations than from those on sandstone and clay. 
The usual legal standard for the temperature of milk when delivered 
to the consumer is 50 °F., and no clean milk will spoil in handling and 
delivery if kept at this temperature. 

Commercial, Forms of Milk. 

The trade has found it desirable to treat milk in various ways for 
special purposes. Definitions are given below of some of these spe- 
cially prepared milks: 

"The following notes are offered in the nature of explanations of 
certain terms which, though very frequently heard among dairymen 
and regularly met with in dairy literature, are nevertheless often 
used inaccurately and sometimes in a way intentionally misleading. 

The many terms, such as aerated milk, filtered milk, etc., which are 
everywhere well understood are not included. Other terms, such as 
malted milk and lacto preparations, are omitted because they apply 
to manufactured food products rather than to forms of milk. 

Standard milk. — The variable nature of milk makes it impossible to 
state without, chemical analysis the Quantity of fat or other con- 
stituents to be found in any given sample. While numerous factors 
such as the breed of cows and the stage of lactation affect the com- 
position of the milk, the variations, nevertheless, are within limits 
capable of being defined with sufficient accuracy and fairness for 
practical purposes. Nearly every country has found it necessary to 
•establish in one way or another certain minimum requirements. 
Milk to be considered unadulterated in Great Britain, for instance 
must contain 3.5 per cent of milk fat and 8.5 per cent of solid matter 
other than fat. In this country the requirements vary in the dif- 
ferent States. In matters concerning the National Government, milk 
in order to be designated as standard must conform to the following 
definition proclaimed by the Secretary of Agriculture: 

'Milk is the fresh, clean, lacteal secretion obtained by the complete 
milking of one or more healthty cows, properly fed and kept, exclud- 
ing that obtained within fifteen days before and ten days after 
calving, and contains not less than eight and one-half (8.5) per cent 
of solids-not-fat, and not less than three and one-quarter (3.25) per 
cent of milk fat.' 

Standard milk is therefore milk which conforms to certain require- 
ments. These are commonly but not always of a chemical nature. 
In some cities bacteriological standards have been established. These 
specify usually a maximum number of bacteria per cubic centimeter 
allowable in milk offered for sale. 

Standardized milk, Blended milk. — These terms are applied to milk 
which has been so modified as to contain a definite amount of one or 
more of its constituents. The most important and at the same time 
the most variable constituent is fat. To standardize milk as regards 



28 

fat it is simply necessary to add or remove a certain amount of this 
constituent or to add or remove a certain amount of skim milk. De- 
tailed directions for this purpose are given in Bulletin 75 of the 
Illinois Station. To cite an illustration from this bulletin, 1,600 
pounds of milk containing 3.2 per cent of fat may be standardized 
to 4 per cent of fat by removing 320 pounds of skim milk. A simple 
method of determining the amounts of skim milk and whole milk, or 
of milks containing different percentages of fat which should be 
mixed in order to secure a product having a desired fat content is 
given by Prof. R. A. Pearson in a reading-course bulletin of Cornell 
University. 

Draw a rectangle and write at the two left-hand corners the per- 
centages of fat in the fluids to be mixed, and in the center place the 
required percentage. At the upper right-hand corned put the number 
which represents the difference between the two numbers standing 
in line with it — i. e., the number in the center and the one at the 
lower left-hand corner. At the lower right-hand corner put the 
number that represents the difference between the two numbers in 
line with it. Now let the upper right-hand number refer to the upper 
left and the lower right hand to the lower left, then the two right- 
hand numbers show the relative quantities of the fluids represented 
at the left-hand corners that must be combined to give a fluid of 
the desired standard which is represented in the center. * * * 

If it is wanted to mix the milks from two dairies testing 4.9 per 
cent fat and 3.5 per cent fat to produce a 4.6 per cent milk, the 
diagram shows these milks must be mixed in the proportion of 1.1 
to 0.3 or 11 to 3. Thus: 




If we have 120 pounds of the 4.9 per cent milk we must mix with it 
32.7 pounds of 3.5 per cent milk, as is shown by this proportion: 
11:3::120:32.7. 

Modified milk, Humanized milk. — These terms are applied fre- 
quently to cow's milk specially prepared for infant feeding. The 
most important difference between cow's milk and human milk lies 
in the proteids or nitrogenous constituents which are greater in 
amount in cow's milk. By allowing a cow's milk to stand for several 
hours, taking the top portion, and diluting this with water with the 
addition of milk sugar, a product may be obtained which corresponds 
in percentages of fat, proteids, and milk sugar to human milk. The 
modifications which have been suggested and the ways of making 
them are very numerous. 

Certified milk. — This term, though registered as a trade-mark in 
1904, is now quite generally used with reference to milk produced 
and handled under conditions approved by some responsible organi- 
zation such as a medical society. An organization of this kind exer- 
cises supervision over the health of the cows, the cleanliness of the 
dairy, the health of employees, the chemical composition and bacterial 
content of the milk, and other matters having a bearing upon the 
wholesomeness of the milk and furnishes a dairyman, complying 
with the specified requirements, a statement certifying to the purity 
of his product. 

Guaranteed milk. — The term 'guaranteed' is often applied to milk in 
its ordinary sense. It merely means that the producer agrees to 



29 

deliver milk of a certain composition or quality, and it should carry 
weight only in proportion to the reliability of the party making the 
guaranty. 

Sanitary milk. — This is a term applied somewhat indefinitely to 
milk produced and handled under conditions considered necessary to 
secure a pure, wholesome product. It is often applied by dealers, for 
purposes of advertising, to milk produced under decidedly insanitary 
conditions. The term 'hygienic' is similarly abused. 

Pasteurized milk. — This term should be applied only to milk which 
has been heated sufficiently to destroy most of the active organisms 
present. Bacteria of one kind or another are invariably present in 
milk obtained under ordinary conditions. Some of these cause sour- 
ing of milk, while others may occasionally be disease-producing 
forms, such as tubercle bacillus. Milk may be heated enough to 
destroy all the organisms present, but when this is done it has ac- 
quired a cooked taste which is more or less undesirable. To avoid 
this the temperature of heating should not exceed 185° P., 'and at the 
same time to secure destruction of any considerable number of 
the organisms present, it must not be below 140° F. When the 
higher temperature mentioned is used the period of heating may be 
very short, but when the lower temperature is employed it must be 
prolonged in order to secure the same results. Pasteurization there- 
fore merely checks fermentation. It does not destroy all of the 
organisms present. It should, however, destroy all disease-produc- 
ing organisms likely to gain access to milk. 

Sterilized milk. — This is milk in which all organisms have been de- 
stroyed. It is not always accomplished by merely boiling the milk 
unless the boiling is repeated on two or three successive days. Higher 
temperatures than the boiling point are necessary to assure steriliza- 
tion or the complete destruction of all organisms at one applica- 
tion of heat of fifteen to thirty minutes' duration. Much of the so- 
called sterilized milk is by no means free of living organisms. 

Clarified milk. — In passing through a centrifugal separator much 
of the solid impurities in milk remains in the separator slime. A 
mixture of the skim milk and cream so obtained is often referred to 
as clarified milk. 

Carbonated milk. — This is milk put up in bottles and charged with 
carbon dioxide or carbonic-acid gas. 

Homogenized milk. — This is milk in which the fat globules have 
been broken up by mechanical means into very fine particles, which 
show no tendency to rise to the surface, as do the fat globules of or- 
dinary size. In accomplishing this purpose the milk is usually forced 
through capillary tubes and against a resisting surface. The force 
of impact causes the breaking up of the globules and thus makes a 
more perfect emulsion out of the milk. The process is protected by 
patents in various countries. 

Condensed milk, Evaporated milk. — This is defined by the Secretary 
of Agriculture as milk from which a considerable portion of water 
has been evaporated and which contains not less than 28 per cent of 
milk solids, of which not less than 27.5 per cent is milk fat. The 
sweetened product contains varying percentages of added sugar. 

Desiccated milk. — This product, which is usually referred to in 
this country as milk powder, is prepared from whole or skim milk 
by patented processes." 

In drawing up the above definitions Dr. H. W. Lawson compiled 
the rulings and opinions of various sanitary officers in State and 
Federal service. 



30 

Milk of Mammals Other Than Cows. 

In this country the milk of mammals other than cows is not much 
used. Milch goats, however, are gradually coming into favor, and 
notes on the composition of the milk of other mammals may be of in- 
terest for purposes of comparison. 

Human milk. — Human milk is chalky white in color and watery 
m appearance. A yellowish color may be noted if the proteid content 
is high. It is rarely sweet, usually of an alkaline reaction. Accord- 
ing to Richmond the average composition is water 88.04 per cent, fat 
3.07, sugar 6.59, proteids 1.97 and ash .26. Great variations are ob- 
served in the constituents. Thus the fat may vary from .5 to 9 per 
cent, the sugar from 4 to 9, the proteids from .8 to 5.5, and the ash 
from .09 to .5. The proteids are not curdled by rennet, the sugar 
crystallizes in rhomboid plates, and the fat is low in volatile acids. 

Ewe milk. — According to Fleischmann the composition of ewe's 
milk is, on an average, water 83 per cent, fat 5.3, sugar 4.6, casein 
4.6, albumin 1.7, and ash .8 per cent. The casein is coagulated by 
rennet, the curd being firmer than that of cow's milk. The fat may 
be separated by the centrifugal or dilution methods but does not rise 
on standing, on account of the great viscosity of the milk. 

Goafs milk. — Konig gives the following composition of goat's milk : 
water 85.71 per cent, casein 3.2, albumin 1.09, ash .76, sugar 4.46 
and fat 4.78. The various constituents closely resemble those of cow'a 
milk in character, but the fat is very white. 

Reindeer. — According to Werenskiold the specific gravity of rein- 
deer milk is 1.0477. The melting point of the fat is higher than that 
of cow's milk. The average composition is water 64.25 per cent, ash 
1.43, fat 19.73, sugar 2.61, casein 8.69, albumin 1.66, globulin .56, 
amids .56, other substances .51. 

Hog. — The milk is thick and strongly alkaline. The specific grav- 
ity is 1.0128. The average composition is water 84.04 per cent, pro- 
teids 7.23, ash 1.05, sugar 3.13, and fat 4.55 per cent. The fat 
content is sometimes as high as 12 per cent. 

Mare. — The total solids seldom reach 10 per cent and the fat 1.5 
per cent. The milk is always alkaline. The average composition is 
water 90.78 per cent, casein 1.24, albumin .07, ash .35, sugar 5.67, and 
fat 1.21. 

^ ss> — The milk of the ass was used by the ancients for bathing pur- 
poses. It is very thin. The average composition is water 89.64 per 
cent, casein .67, albumin 1.55, ash .51, sugar 5.99 and fat 1.64. 

Mule. — The milk of the mule is white, alkaline and does not coagu- 
late. The average composition is water 91.5 per cent, proteids 1.64, 
ash .38, sugar 4.8, and fat 1.59 per cent. 



31 

Camel. — The milk of the camel resembles human milk in coagu- 
lating with light flakes. It is pure white and sweet, The average 
composition is water 86.57 per cent, proteids 4, ash .77, sugar 5.59, 
and fat 3.07 per cent, 

Indian buffalo. — Buffalo milk is much used in India, the Philip- 
pines, Hungary and elsewhere. The average composition is watef 
81.41 per cent, casein 5.85, albumin .25, ash .87, sugar 4.15, and fat 
1.47. 

7,ebu. — This is one of the most important milk animals in India. 
The average composition of the milk is water 86.13 per cent, fat 4.8, 
casein 3.03, sugar 5.34, and ash .7 per cent. 

Dog. — The average composition of dog's milk is water 75.44 per 
cent, casein 6.1, albumin 5.05, ash .73, sugar 3.08, and fat 9.57 per 
cent . The yield of milk is greater on a meat than on -a vegetable diet. 
The reaction of the milk is always acid. 

Cat. — The composition of cat milk on an exclusive meat ration is 
as follows: water 81.63 per cent, casein 3.12, albumin 5.96, ash .58 
sugar 4.91, and fat 3.33 per ent. 

Porpoise. — The milk is yellow, thick and of a fishy odor. The 
total solids amount to about 58 per cent, The average compositin is 
water 41.11 per cent, proteids 11.19, ash .57, sugar 1.33 and fat 
45.8 per cent, 

Rabbit. — According to Pizzi the average composition of rabbit's 
milk is as follows: water 69.5' per cent, fat 10.45, proteids 15.54, 
sugar 1.95, ash 2.5 per cent. The specific gravity is 1.0493. 

Elephant. — The milk of the elephant is characterized by its high 
fat and low proteid content. The average composition is water 67.85 
per cent, proteids 3.09, ash .65, sugar 8.84 and fat 19.57 per cent. 

Partial analyses have also been made of the milk of the lama, whale, 
bison, catalo and other mammals but the data thus obtained are of 
little interest in this connection. As with cows so with other mammals 
the milk is influenced in its composition by such factors as breed, age, 
size, period of lactation, individuality, exercise, excitement, estrum, 
weather, seasons, food, disease, etc. 



32 



CHAPTER II. 

ABNORMAL MILK. 

In the foregoing chapter an account has been given of the biology, 
physics and chemistry of normal milk. In the present chapter it is 
proposed to discuss the various abnormal conditions which may be met 
with in milk. The abnormal features of milk may be due to striking 
irregularities in composition, abnormal colors due to added coloring 
matters or bacteria, abnormal odors or flavors due to improper feeding 
stuffs, absorption of disagreeable odors, to bacteria, a ropy or slimy con- 
dition, abnormalities due to conditions of the udder, ingestion of drugs 
or harmful plants or to the presence of pathogenic bacteria, toxins and 
antitoxins, to bacterial changes producing milk poisoning, to the 
presence of dirt or to adulterations. In the following paragraphs 
these abnormalities are briefly discussed in order. 

Milk Abnormal in Composition. 

The usual composition of normal milk as determined by the analy- 
sis of thousands of samples has been studied in chapter I. The com- 
position of milk as discussed in that chapter may vary considerably 
as a result of the influence of various factors but occasionally quite 
striking irregularities appear in composition. For example, the fat 
content may be decidedly too low or too high, varying from 2 to 15%. 
In a case reported by Cooke the fat content was 14.6% in the milk 
of a cow shortly before calving. In an instance reported from Ger- 
many a cow at a similar stage of lactation, that is, when almost dry, 
gave milk which contained 42% of solids, of which 25% was fat. 
The cow was later slaughtered and found to be diseased. Milk may 
occasionally be watery without showing any adulteration or skim- 
ming. Such milk has a low specific gravity and is bluish in color. 
Sometimes a low percentage of fat is seen in milk obtained during 
the period of heat in cows, or as a result of improper care and feeding. 
It is obviously impossible to draw hard and fast lines for the minimum 
and maximum fat content of normal milk. In general, however, it is 
considered that milk containing less than 2% or more than 10% of 
fat is abnormal and that the conditions surrounding the case should 
be investigated. 

Occasionally milk possesses a salty flavor due to an excess of ash 
content and an unusually small amount of lactose. Milk of this 
character is most often obtained in cases of garget. Similarly colos- 
trum obtained during the first few days after calving possesses a 
high content of mineral matters and sometimes shows a decidedly 



33 

salty flavor. In rare instances milk appears to be sandy, not as a result 
of the addition of ordinary sand from careless handling but to the 
presence of small concretions of carbonate of lime which are found 
in the milk ducts under abnormal conditions. 

Abnormal Colors Due to Added Coloring Blatters and 

Bacteria. 

Added coloring matter. — In some localities a demand is made for 
milk of a decidedly yellow color under the supposition that the con- 
sumer is receiving more cream than in milk which shows a bluish 
tinge. In order to lend this yellowish color to milk coloring matters 
have been added to a slight extent. In the examination of 23,000 
samples of milk in Massachusetts, 151 samples contained a foreign 
coloring matter. The color chiefly used was annate but aniline orange 
and caromel had also been used in a few instancees. About 95% of 
the samples containing foreign coloring matter were found upon anal- 
ysis to have been diluted with water. In these cases therefore the 
coloring matter was added in an attempt to obscure the adulteration 
of the milk. Saffron and more rarely other coloring matters have 
been added to milk for the same purpose. 

As is well known a number of feeding stuffs exercise an influence 
upon the color of the milk. Grass, corn meal, corn silage and various 
succulent feeds usually have the effect of giving a rich yellow color 
to the milk, while dry hays, cottonseed meal and certain other feeding 
stuffs may have the opposite effect. Rhubarb has a tendency to pro- 
duce a yellowish or in some cases a reddish tinge in milk. A brown 
coloration of the milk may be due to foreign substances such as filth 
or may be caused by the growth of certain fungi. In rare instances 
milk may show a greenish tinge due to' a high fat content and im- 
perfect emulsification or to the presence of fluorescent bacilli and the 
formation of pus in the udder. 

Colors due to bacteria. — A number of well known abnormal colora- 
tions of milk are due to bacteria multiplying in it. 

Blue milk was in former years reported more frequently as an 
abnormal condition of milk than at present. It is due to the develop- 
ment of Bacillus cycwiogenes. Milk infected with this bacillus is at 
iirst not different, at least to the naked eye, from perfectly normal 
milk. Usually, however, it does not sour as rapidly as normal milk. 
After standing a short time small blue spots appear upon the surface 
which increase in size and gradually become confluent, covering the 
whole surface of the milk by the time it has soured. The blue surface 
coloring is in most cases complete within a few hours. In milk which 
contains a large percentage of fat the blue coloration does not appear 
so strikingly even when a bad infection with Bacillus cyanogenes has 
taken place. The blue color is at first pale, but if the milk is allowed 
to stand for several days the color finally becomes azure. The color 



34 

is most intense upon the upper surface but it is recognizable through- 
out the whole mass of milk. The coloring matter produced by tliia 
bacterial infection has been supposed by some investigators to belong 
to aniline dies. This supposition, however, has been thrown in doubt 
by other bacteriologists. The bacillus which causes blue milk may 
be readily destroyed by subjecting the milk to a temperature of 55 
degrees C. for ten minutes. Rarely blue milk appears in epizootic 
form and seems to affect the product of the whole herd. Tn most 
instances, however, the infection comes from a single cow in the herd 
and as soon as her milk is excluded the rest of the milk appears 
normal. 

Red milk has long been known to occur with comparative infre- 
quency. A striking red color may appear on various other food 
materials, particularly bread and potatoes. This coloration is clue 
to the growth of Bacillus prodigiosan and may be easily distinguished 
from the pinkish or reddish color due to the presence of blood in 
milk. If any doubt is felt regarding the cause of the red color, the 
inoculation of a small amount of the material into any of the ordinary 
nutrient media will show the prompt development of a red color due 
to Bacillus prodigiosus if this organism is present. The bacillus in 
question does not thrive well in the presence of acid and its growth 
is therefore checked by the rapid development of the lactic acid ba- 
cilli. Occasionally a red coloration is produced in milk by the growth 
of a species of sarcina. 

Yellow milk is occasionally reported as an abnormal condition. 
According to Adametz this is due to the growth of Bacillus synxanthus. 
A microscopic examination of yellow milk will reveal the presence of 
crystalline bodies, cholesterin, needle crystals, lymph cells and disin- 
tegrated fat globules. A number of bacteria have been described by 
Conn as producing a yellow color. Some of these organisms rapidly 
produce a bright coloration, while others act more like rennet, causing 
a coagulation of the casein followed by digestion and later by the 
appearance of a yellow color. 

Other colors such as green, black and brown have occasionally been 
referred to' as occurring in milk, but as stated by Conn they cannot be 
considered as ordinary dairy infections for the reason that they occur 
only in bacteriological examinations during which bacteria are grown 
on a sterilized milk medium. The abnormal coloration of milk due 
to the action of bacteria is no longer a serious matter in commercial 
dairying for the reason that the means for preventing it are thoroughly 
understood. Sunlight and cleanliness particularly in the care of dairy 
utensils prevent the contamination of milk with color-producing 
bacteria. 

Abnormal Flavors and Odoes. 

Flavors and odors due to improper feeding staffs.- — It is a matter of 
common knowledge that milk readily absorbs the odors which may pre- 



35 

vail in the air of stables or milk rooms. The absorption of odors takes 
place more rapidly in warm than in cold milk. In a test of the ab- 
sorption of the odors of volatile oils Russell found that the odor of 
peppermint was absorbed more readily than that of wintergreen or 
cinnamon. Occasionally disagreeable odors may develop in milk not 
as a result of absorption from various foreign substances but appar- 
ently from a contamination with bacteria, particularly bacillus lactis 
foetidus. According to Thorner this bacillus in milk may produce a 
putrid odor resembling that of some ammoniacal compounds. 

Nearly all feeding stuffs transmit a specific flavor and odor to 
milk which in many instances, however, are so faint as to escape 
recognition except after some experience along this line. Not only 
the flavor and odor of feeding stuffs may be transmitted to milk but 
also other active principles contained in these plants. According to 
Tencre palm nut cake when fed in quantities not exceeding four lbs. 
daily gives an agreeable specific flavor to milk and the butter made 
from it. A number of other oily feeds such as linseed meal, peanut 
meal, cottonseed meal, etc., not only exercise an effect upon the firm- 
ness of butter and its color but also lend a barelv perceptible flavor 
to it. 

Distillery and brewery by-products are quite generally objected to 
as feeding stuffs for dairy cows for the reason that disagreeable odors 
and flavors are sometimes believed to be transmitted into the milk 
from these feeds. According to the experiments of Lindsey, in Mas- 
sachusetts, however, no specific odor or flavor was given to milk as 
a result of feeding distillers' grains, brewers' grains or malt sprouts. 
Nevertheless, some milk dealers, particularly in New York Citv, 
object to the use of any of these feeding stuffs by the farmers who 
furnish them milk and in one or two instances even corn silage is 
mentioned as an undesirable feeding stuff. In a number of German 
experiments in which distillery residue was fed to cows the milk and 
butter from these cows had an objectionable potato like or alcoholic 
odor. Weller found that in a large herd of cows kept at a distillery 
the milk had an irritating after flavor and upon examination showed 
the presence of .9% °f alcohol. These cows received no grain except 
distillery residue and it was soon found that the alcohol in this ma- 
terial could be readily driven off by the use of steam after which the 
slump had no bad effect upon the milk. In certain French tests of 
this matter no alcohol was detected in the milk of cows fed on distillery 
malt when small quantities of this material were fed. In general it 
appears that neither the flavor nor odor of alcohol appears in milk 
unless considerable quantities are used in feeding. 

As already indicated a great many substances may be transmitted 
from the blood of the cow and from the feeding stuffs to the milk. 
Nearly all of the volatile fats and oils which are derived from fat 
substances may thus come to lend a specific flavor to the milk. The 



36 

flavors and odors which are most desirable come from feeding stuffs 
which are held in highest esteem for the production of milk, while 
the undesirable odors are largely due to the ingestion by cows of onions, 
leeks, garlic, turnips, cabbages, various kinds of wild bitter herbs 
and brush, fish, etc. The animal odor which appears in freshly drawn 
milk is objectionable to many individuals but disappears soon after 
the milk is drawn under the influence of aeration and cooling. This 
animal odor, however, is to a considerable extent due to the volatile 
odors which are derived from the food materials consumed by the cows. 
In cases where the dairyman desires to feed considerable quantities of 
turnips, cabbages, carrots, brewers' grains or other material which 
may give rise to a specific flavor or odor in milk, the matter may be 
easily adjusted by feeding these materials after milking rather than 
before. The odors then disappear and Are not noticed in the milk 
obtained at the next milking. No satisfactory methods have been 
devised for removing specific odors due to plants after they once gain 
entrance to the milk. In the case of the odors of turnips and cabbages 
they usually disappear when milk is pasteurized. This is not, true, 
however, for onions and garlic. In stables where silage is fed ex- 
tensively, the odor of this material may permeate the milk unless it 
is removed promptly from the stable. 

A bitter taste may be given to milk whenever cows eat wormwood 
in pastures or skunk cabbage. The disagreeable flavors which are 
often complained of in milk in early spring and at other seasons of 
the year when the pasture is poor are for the most part due to the 
fact that at such times the cows may accidentally eat small quantities 
of plants with bitter taste growing among the grass or in consequence 
of short pasturage may be tempted to eat various native weeds which 
otherwise would: not be touched. This constitutes an argument of 
considerable force in favor of using cultivated pastures only and 
adopting a system of rotation which includes the use of meadows for 
pasture after they have been used for hay purposes for a number of 
years. 

In New York Harding reports the occurrence of a fishy flavor in 
milk. The taint was so strong as to render the milk unfit for use. 
An investigation of this case failed to disclose a satisfactory explana- 
tion of the flavor. The dairyman in question used more than ordinary 
care in handling the herd and the milk. The flavor seemed to be 
confined to the milk of a single cow and disappeared from the herd's 
milk as soon as the milk of this cow was excluded. An examination 
of the pasture did not show the presence of any weed which might 
be supposed to cause the trouble. 

Dombrowski carried on a number of feeding experiments with 
various plants and feeding stuffs to determine the extent to> which the 
flavor of these materials was transmitted to milk. The food stuffs 
used in these experiments included anise seed, fennel seeds, garlic, 



37 

carrots, alizarin, etc. The odor of anise seed, fennel and garlic was 
readily transmitted to milk so as to give a strong flavor. The odor of 
garlic did not disappear after boiling the milk and allowing it to cool 
for 15 hours. On the other hand the flavor and odor of fennel and 
anise disappeared as the result of boiling the milk. The specific 
flavors of other plants were recognized in the milk and it appears 
that the volatile materials which determine the presence of flavors and 
odors in plants are much more easily transmitted to milk than the 
specific coloring matters of these plants. Alizarin, however, fennel 
seeds, carrots, chrysophanic acid and garlic affected the color of the 
milk. 

Absorption of odors. — It is well known that milk readily absorbs 
odors which may be present in the air of stables or milk rooms. To- 
bacco smoke is quickly absorbed and lends a specific odor to the milk 
which persists for some time. It is practically impossible to obtain 
milk entirely free from the odor of tobacco if the dairy attendants 
smoke during milking and the various processes in handling milk. 
Many other drugs with penetrating or pungent odors are likewise 
absorbed by milk. In this class of substances we may mention iodo- 
form, carbolic acid, turpentine, chloride of lime, formaldehyde, etc. 
Milk exposed for a few minutes in an atmosphere containing formal- 
dehyde fumes to the extent of 1 to 100,000 showed a decided reaction 
of the fumes when examined by Bordas. The many observations 
which have been made along this line indicate that great care should 
be exercised to exclude disagreeable odors from the stables and milk 
rooms. Dombrowski also observed a. rapid absorption by milk of the 
odors of iodoform, anise seed oil, carbolic acid, turpentine, formalde- 
hyde and chloride of lime. The odor of iodoform persisted in the 
milk for twelve hours. 

Abnormal flavors or odors due to bacteria. — Bitter milk has often 
been referred to as a specific condition due to the presence of bacteria 
in the milk. It is however not always due to bacteria but may be 
caused by rag weed, wormwood, lupines as well as various other plants., 
and* by the prevalence of certain bacteria in the milk. In a few in- 
stances bitter milk has been observed as a result of the absorption of 
the odor of urine from cows showing an excessive pollution. In at 
least one instance bitter milk was found to be due to feeding Swedish 
turnips which had been washed in foul water. The milk in this case 
was somewhat frothy and exhibited an active process of fermentation. 

Harrison investigated the cause of bitter flavors which were ab- 
sorbed in milk and cheese. A yeast was isolated from samples of the 
curd and was also found in the milk. This yeast was Torula amara. 
The yeast was found in the milk of nearly every farm which was 
taken to a certain cheese factory in which the trouble occurred to the 
greatest extent. The use of water at a temperature of 200 °F. in 
washing cans was not sufficient to destroy the yeast in this case. 



38 

As has been shown by Conn, a large variety of bacteria may have 
the effect of producing a bitter flavor in milk. As a rule the taste 
appears only after the milk has been allowed to stand for a consider- 
able period of time. Bitter milk is of comparatively rare occurrence 
and a bitter flavor is much less often observed in milk than in cheese. 
Bitterness may develop slowly however in sterilized milk as a result 
of the growth of certain bacteria which have not been killed by heat. 
The bacteria which cause bitter milk may sometimes be found in the 
milk ducts and upon the udder of cows and are best destroyed by 
washing the udder with a solution of borax and injecting week solu- 
tions into the milk ducts. 

Swithinbank looks upon the occurrence of bitter milk as a rather 
serious problem for the dairy bacteriologists for the reason that al- 
though it may occur rather rarely it is quite difficult to eradicate 
after it has once appeared on the dairy farm. It would seem that 
bitter milk may be in part due to the rapid decomposition of the 
casein of milk and may possibly be connected vfith or one of the 
stages of the formation of tyrotoxicon. The organisms which have 
been referred to as causing bitter milk include the bitter milk bacillus 
of Weigniann, Conn's micrococcus of bitter milk, specific bacilli de- 
scribed by Bleisch, LofTler, Hueppe, Freudenreich and a number of 
other organisms. As studied by Swithinbank, one of these species of 
bitter milk producers may infest a farm or dairy for months and in 
some cases for years before complete success is had in its eradication. 
Several investigators have reported the rather infrequent occur- 
rence of another defect of milk in which a. soapy flavor may be 
detected. Soapy milk has been found in at least one instance to be 
due to an organism which occurred in considerable abundance on 
straw used for bedding. The milk in which this bacillus was found 
did not coagulate but became somewhat ropy and showed a decidedly 
soapy flavor. Fortunately this trouble is of rare occurrence and 
yields readily to the application of modern dairy hygiene. 

Sour milk must be considered as an abnormal condition of milk 
from the standpoint of the patron of a milk route. Milk must be 
allowed to sour for the production of butter and, as is stated in chapter 
XII, milk is never free, at least under ordinary conditions, from lactic 
acid bacteria. When the numbers of these bacteria, however, are 
kept within reasonable limits, and low temperatures utilized in the 
handling and preservation of milk the bacteria do not multiply to> a 
sufficient extent to cause more than the slightest increase in acidity by 
the time the milk is delivered to the consumer. In the case of soapy 
milk already referred to souring sometimes fails to take place within 
the usual period. On the contrary a pungent odor may develop and 
also a sweetish flavor. In the case of milk which has not been handled 
with sufficient care to keep down the numbers of lactic acid bacteria 
foaming may appear when the milk is run through a separator. Ac- 



39 

cording to Siedel this is mainly due to the fact that some of the casein 
has been dissolved by the action of the lactic acid. The foaming is 
more pronounced at higher temperatures. 

Alcoholic fermentation may appear in milk as the result of con- 
tamination with yeasts. Certain yeasts have the power of breaking 
up milk sugar and producing carbonic acid gas and alcohol. The 
amount of alcohol produced in milk, however, is very small as com- 
pared with that which appears in the alcoholic fermentation of sugars 
in other products. A number of artificial beverages are made from 
milk by inducing alcoholic fermentation in it. The chief beverages 
of this sort are koumiss, kephir, matzoon and leben. These milk 
products will be discussed in chapter XV. 

Ropy ok Slimy Milk. 

A large variety of bacteria have been shown to be capable of causing 
a ropiness or sliminess of milk and cream. These organisms have 
been studied by Conn, Ward, Tillman, Gruber, Marshall and many 
other dairy bacteriologists of Europe and this country. A sliminess 
in milk somewhat resembling that caused by bacteria is occasionally 
observed in diseases of the udder, particularly garget and in Norway 
it has been found that a slimy condition may be produced in milk 
by adding a few of the leaves of pinguicula. 

Schmidt was the first to describe ropy milk in 1882 and since that 
time many investigations of the ropy condition of milk have' been 
undertaken and twelve or more species of bacteria isolated as causing 
this condition. The temperature at which sliminess appears most 
rapidly after the milk has become contaminated is about that of the 
ordinary living room. According to Stohmann the formation of the 
slimy or ropy material in milk takes place at the expense of the lac- 
tose. The milk serum takes on a strongly acid reaction during the 
process of fermentation which produces ropiness. The ropy material 
may easily be obtained in the formation of a precipitate if the lactose 
solution or milk in which the fermentation has taken place is diluted 
with alcohol. 

The organism which most commonly causes ropiness is bacillus 
lactis viscosus. As stated by Conn, this organism grows so rapidly 
that it is not greatly checked even by the presence of lactic acid bac- 
teria. The slimy milk bacilli come for the most part from unclean 
water and these gain entrance to the milk vessels in the water used 
for washing them. This indicates a. practical way of eliminating 
the trouble since it yields easily to the thorough cleansing of milk 
utensils. 

In the investigations carried on by Ward at Cornell University, 
the Bacillus lactis viscosus was found to be the chief cause .of slimy 
milk. In preventing this trouble it appeared to be most desirable to 
scald thoroughly all pails and other utensils as well as strainer cloths 



40 

after each using. Since as has already been stated the organism 
which causes slimy milk is usually present in the water, the trouble will 
obviously be perpetuated by continuing to use water which has not 
been boiled. On infected premises no water should be used in cleans- 
ing milk utensils until it has been brought to a boiling temperature 
so as to destroy the bacteria. 

Ropy milk is objectionable more on account of its appearance than 
on account of any known harmful results caused by drinking it. The 
peculiar condition of ropiness may not appear until after the milk 
has been allowed to stand for twenty-four to thirty-six hours. If the 
milk is infected with the slimy milk bacillus the cream and milk on 
pouring shows long fine viscous threads. It, is absolutely necessary 
in controlling ropiness in milk to prevent the contamination of the 
milk with the bacteria which cause the trouble, for these organisms 
will multiply sufficiently to produce ropiness even at a temperature of 
45 to 50°F. 

According to Tillmans milk when contaminated with the slimy milk 
bacillus undergoes a number of chemical as well as other changes. 
The solid constituents are somewhat diminished by the decomposition 
of lactose, the acidity is increased, the fat is slightly altered and the 
casein is peptonized to some extent. The organism which causes slimy 
milk has been in some cases isolated from straw as well as from water 
According to Marshall the bacteria of slimy milk may be found upon 
the hair of the udders and flanks of cows and possibly upon the hands 
of milkers. This suggests the desirability of exercising all proper 
precautions in sanitary milking and handling milk. Rarely cream 
has been observed to possess an oily and slightly gelatinous consistency 
while the remainder of the milk possessed normal characters. This 
condition is closely related to ropiness but is readily distinguishable 
from it, although it appears to be due to bacterial infection of the 
milk. 

Abnormalities Due to Conditions of the Uddepw 

It is impossible within the limits set for this chapter to> discuss all 
of the pathological conditions which may appear in the udder of cows 
and which may affect the composition or appearance of the milk. In 
general all infectious diseases during the course of which lesions 
appear in the udder result in the production of milk abnormal in 
one or more respects. 

The udder of modern dairy breeds of cows has been developed to 
such a large size that it is frequently exposed to bruises of more or 
less serious nature. Such contusions may cause in turn the secretion 
of abnormal milk. If the blow or bruise be severe enough to rupture 
small blood vessels, blood may escape into' the secreting tissue and 
the hemoglobin of the blood or actual blood corpuscles may escape 
with the milk. Following upon severe blows a swelling or edema may 



41 

occur with more or less extensive inflammation. In all such cases 
lymph or blood serum will appear in considerable quantities in the 
inflamed tissue and will escape with the milk or at any rate have 
the effect of changing the composition of the milk. Wherever an in- 
flammatory condition prevails the number of white blood corpuscles 
soon rises far above the normal and an estimation of the leucocytes 
in the milk will show that they are present in too high numbers. 

As a result of contusions or from other causes small blood vessels in 
the udder may become obstructed by the formation in them of solid 
plugs of the blood constituents. This condition is known as throm- 
bosis and may lead to the disintegration of the red blood corpuscles 
and the secretion of red coloring matter with the milk. If the cow's 
udder should receive a blow of sufficient violence to lacerate the tissues, 
small particles of secreting cells or other tissue material might gain 
entrance to a blood vessel of the udder so as to stop the flow of blood 
when the foreign body reaches a small part of the vessel. This would 
lead to the condition known as embolism, although emboli are more 
often the result of the dislodgement of thrombi in the blood vessels 
aud their subsequent blockade in small parts of the vessels. 

The formation of thrombi and emboli are often due to the presence 
of ferments in the blood which cause the actual coagulation of small 
particles of blood into solid masses which are later caught in the 
capillaries or small blood vessels. Wherever these pathological condi- 
tions prevail the disintergration of the embolic material will necessarily 
have an influence upon the character of the milk. Small quantities 
of fibrin and mucuous threads may appear, together with large num- 
bers of white blood corpuscles and epithelial cells. 

In all cases of mammitis the number of white blood corpuscles in 
the milk is enormously increased. In all cases of contagious mam- 
mitis, pathogenic streptococci will also be found in the milk obtained 
from affected quarters of the udder. During the progress of mammitis 
or garget red blood corpuscles will escape into the milk to a greater 
or less extent and will give rise to bloody or pink milk. In all cases of 
tuberculosis and actinomycosis tubercles may be formed in the udder 
giving rise to swellings of various size and tissue changes, which in 
turn cause alterations in the character of the milk. In all cases where 
the udder is affected by these diseases the milk should *be absolutely ex- 
cluded from the market except after boiling and even after steriliza- 
tion objection may be raised to it on the ground of its changed chemical 
composition and the possible presence of toxins or ferments which 
may be produced during the progress of the disease. The variations 
in the composition of milk due to the presence of tubercles or other 
disease processes in the udder are not uniform. The changes usually 
affect the relative proportion of the normal constituents of milk but 
these proportions are not always changed in the same manner. Oc- 
casionally also an increased quantity of salts and mineral matters are 
observed in the milk. 



42 

Tumors may affect nearly all parts of the body. The term tumor 
is used to denote a tissue proliferation of persistently progressive 
character changing the appearance and function of the affected part. 
During the progressive growth of tumors an excessive accumulation 
of tissue appears caused by cells of the surrounding tissue which 
appear to change their nature, become essentially parasitic and 
invade the tissues in which the enlargement takes place. During 
the growth of tumors a great variety of metabolic products 
and decomposition substances are set free. These substances may 
exercise toxic influences upon the animal in which the tumorous 
growth occurs and if the tumor is located in the udder the toxic prop- 
erties may be transmitted to the milk. Moreover in the inflammatory 
area usually observed around a growing tumor the tissue is extensively 
infiltrated with white blood corpuscles and may also show suppur- 
ative or gangrenous growth. The white blood corpuscles, toxins and 
other products of gangrenous degeneration may be set free into the 
milk. 

According to Pusch bloody milk occurs much more frequently than 
is generally supposed. In many instances the amount of blood which 
escapes into milk is scarcely sufficient to cause a red coloration which 
can be detected. In some instances blood appears in the milk for a 
short time after calving and then disappears. In two cases observed 
by Pusch the trouble could not be attributed to 1 any injurious prop- 
erties in feeding stuffs nor to inflammation of the udder. The cause 
of the presence of blood in the milk was attributed to a general state 
of congestion. Sometimes blood or hemoglobin appears in the milk 
merely as the result of a rupture of a blood vessel in the udder. In 
such cases the trouble may easily be remedied by the infusion of air 
into the udder as is practiced in treating milk fever. 

Not only such diseases as affect the udder specifically may be the 
cause of abnormal conditions in milk, but various other general dis- 
eases may bring about changes in the composition of milk, affecting 
its nutritiousness or wholesomeness. Thus, in addition to those dis- 
eases which will be mentioned in chapters III and XIII, digestive 
disturbances as a rule cause an unfavorable effect upon the composition 
of milk. The milk in such cases coagulates quickly, often within six 
or eight hours after milking, without undergoing the normal process 
of souring. It has therefore an abnormal flavor, yields a cream which 
does not churn readily, or, in some cases, may ferment, foam or exhibit 
a watery, thin and bluish character. Likewise the quantity of the 
milk diminishes or may become almost entirely checked. In cases of 
jaundice the yellow coloring matters of the bile may enter into the 
milk so that it assumes a decidedly yellow coloration. Moreover in 
cases of bloody urine the red coloring matter of the blood passes over 
also in the milk, lending it a pink or reddish color. All serious 
general diseases accompanied with fever cause a diminution in the 



43 

amount of milk and also affect its quality. In some of these diseases 
the pathogenic bacteria are also found in the milk, as will be men- 
tioned below. In diseases during' the course of which suppuration or 
pyemic processes take place, the milk may become thicker than normal, 
somewhat slimy and in serious cases purulent. Occasionally in such 
diseases a greenish color is noted in the milk and a stringy or gel- 
atinous condition. In these cases the condition may somewhat re- 
semble that of ropy milk. 

The changes usually observed in cases of catarrh or inflammation 
of the udder have already been mentioned. Such milk often appears 
rose color or red, or, more rarely, it is thin and grayish white. The 
milk may contain minute flakes or larger clumps of material which 
upon standing or after centrifugal separation may lead to the forma- 
tion of a thick or grayish yellow sediment. In cases of mammary in- 
hammatioii the milk is sometimes salty or at least less sweet than 
usual and may contain slimy flakes or stringy masses or larger coagu- 
lated clumps. In such milk an irregular coagulation may take place 
upon boiling. The coagulated masses are sometimes yellowish and 
sometimes reddish brown and taste salty. In parenchymatous in- 
flammation of the udder the quantity of milk is greatly diminished 
and the color may be a dirty gray. The milk may also show irregular 
coagulated masses. In chronic inflammation of the udder the milk 
becomes watery and of a bluish color. Moreover it does not keep as 
well as normal milk and shows coagulated masses of varying size. 

In all diseases in which pyemia or septicemia occurs, poisonous 
substances are formed which may pass into the milk, rendering it 
actually dangerous. The history of meat inspection has shown that 
the meat of such animals when eaten by man may cause serious cases 
of poisoning and it is probable that the same dangerous toxins are 
frequently found in the milk. 

Abnormalities Due to Ingestion of Drugs and Harmful Plants. 

It has already been stated and it hardly seems necessary further to 
urge that the milk of all seriously sick cows should be excluded from 
the regular milk of the herd in distributing to patrons. This is a neces- 
sary precaution on the ground that such milk may be abnormal in 
composition and may be actually dangerous by reason of its content 
of toxins or pathogenic bacteria. Moreover if such cows are treated 
with medicines it must always be borne in mind that such drugs may 
and usually do pass over into the milk, thus affecting those persons 
who consume it. It has already been shown that this happens in the 
case of strychnine, veratrin, aloes, ether, camphor, chloroform, Glaub- 
er's salts, carbolic acid, iodine, potassium iodide, borax, bismuth, lead, 
zinc, copper, iron, antimony, arsenic, mercury, eserin, morphine, atro- 
pin and various other drugs used as medicines in the treatment of 
cattle. As shown by Glage, iodine readily passes into the milk and 



44 

arsenic may be thus transmitted in such quantities as to render the 
milk poisonous. Mercury, tartar emetic, lead and copper, on the other 
hand, are not transmitted to the milk except to a very slight extent. 
As a rule, however, the milk of cows which have received powerful 
drugs as medicines should not be used. In such cases the composition 
of the milk ordinarily remains normal or nearly so, but the drugs 
may be present in a sufficient quantity to lend the milk a specific 
flavor and action upon the person who drinks it. For a short time 
after the administration, of tuberculin in testing cows for tuberculosis 
small quantities of the tuberculin may be found in the milk but 
ordinarily not in sufficient quantities to render it harmful. 

The transmission of alcohol to milk has already been mentioned as 
occurring when this substance is administered as medicine and also 
when it is present to a large extent in the feed, as, for example, dis- 
tillery by-products. Such feeds may contain enough alcohol to affect 
the milk in a decided manner, not only by the presence of the alcohol 
but by bringing about a pronounced acid reaction in the milk. Oster- 
tag has found that in some cases the milk of cows fed continuously 
upon large quantities of sugar beet pulp may contain enough potassium 
to render it objectonable to adults and particularly to children. Simi- 
larly wild mustard and castor oil cakes are undesirable feed stuffs on 
account of the fact that injurious substances are transmitted from 
them to the milk. In rare instances cows will eat decomposing and 
putrid animal or vegetable substances, including the excrement of 
human beings and other animals. Naturally in such cases a disagree- 
able odor, if no more injurious quality, is transmitted to the milk. 

The list, of harmful or poisonous plants which may injurously affect 
the milk after being eaten by cows is very large. It has been shown, 
for example that calves are sometimes badly affected by drinking milk 
from cows which have eaten feed stuffs containing large quantities of 
ergot. Milk sickness or trembles is a disease which has long been 
known as affecting cows particularly in the neighborhood of swampy 
or low areas throughout the central States. It has also been found in 
numerous instances that the milk of such cows contains the essential 
cause of the disease and may thus transmit the disease to calves or 
human beings. The cause of milk sickness is unknown although many 
suppositions have been made concerning it. Recently it has been as- 
serted that the disease is due to eating white snake root (Eupatorium 
ageratoides) . This plant was said to' cause more or less serious symp- 
toms of disease in cows which eat it but curiously enough the effect is 
far more serious upon those who consume the milk. The symptoms of 
milk sickness in man include nausea, vomiting, headache, trembling 
and pains in the limbs. The toxin or bacteria contained in the milk 
of affected cows is capable of causing the death of children and adults 
who consume the milk, even when the cow herself is not dangerously 
affected. 



45 

Likewise with larkspur, aconite, lupines of various species, death 
cainas, wild parsnip, etc., we have observed instances in which calves 
and lambs at the mother's side were seriously affected and in some 
cases died after the mother had eaten these plants, although the 
mother herself was not seriously poisoned. The danger from poison- 
ous plants is obviously greatest in those regions where cows graze on 
native pastures and where no attempt is made to eradicate wild species 
of plants. Where cultivated pastures are used such plants have little 
or no opportunity to thrive. 

Pathogenic Bacteria in Milk. 

In chapters XII and XIII descriptions are given of the pathogenic 
bacteria which may be found in milk and the extent of their occurrence 
and their agency in transmitting disease to man are discussed. All 
milk which contains pathogenic bacteria must be considered not only 
as abnormal but unfit for consumption and dangerous. 

The pathogenic organisms of greatest importance in milk are those 
of tuberculosis, contagious mammitis, foot and mouth disease, typhoid 
fever, scarlet fever, diphtheria and cholera. The organisms of tuber- 
culosis and contagious mammitis may be transmitted to the milk 
directly from the cow. Tubercle bacilli may also gain entrance to the 
milk from tuberculous attendants, in manure and in other ways. The 
pathogenic organism of foot and mouth disease has not been isolated 
but the virus is present in the milk of all cows in which the udder is 
affected. The virus of typhoid fever, diphtheria, scarlet fever and 
cholera must gain entrance to the milk after it has been drawn from 
the cow. All of these diseases are dangerous or fatal to man and the 
presence of the virus in the milk in any case is sufficient cause for 
excluding it from consumption. 

Toxins, Antitoxins and Other Bacterial Products in Milk. 

During the progress of various infectious diseases toxins, antitoxins 
and other products of the growth of pathogenic bacteria are formed 
in the body and may pass into the milk to a greater or less extent. 
The toxins in such cases exercise an injurious effect upon persons who 
consume the milk, but the antitoxins, antibodies and certain other 
products of bacterial growth may exercise a greater or less immuniz- 
ing effect on the young sucking animal or upon human beings. This 
is true to some extent of nearly if not quite all diseases. The greatest 
interest in this connection has recently centered around the possible 
value of the immunizing substances in the milk of tuberculous cows. 
Von Behring has gone so far as to devise a plan of immunizing calves 
and children against tuberculosis by the use of the milk of tuberculous 
cows. This investigator suggests that since such milk contains the 
antibodies which antagonize the progress of tuberculosis it may be 
highly desirable to leave them in their original state in the milk in the 



46 

hope that their influence will be manifested in protecting against 
tuberculosis the individual who consumes the milk. In carrying out 
this plan Von Behring recommends that the milk of tuberculous cows 
•should not be pasteurized or sterilized since in this process not only 
the tubercle bacilli are destroyed but also the immunizing substances. 
If such milk is treated with formaldehyde to the extent of one part in 
forty thousand it is claimed that the tubercle bacilli will be destroyed 
without thereby affecting the immunizing properties of the milk. The 
use of formaldehyde in milk for any purpose, however, is highly ques- 
tionable and the importance of the immunizing effect of tuberculous 
milk in which the tubercle bacilli have been destroyed remains to be 
demonstrated. 

Not only are the toxins and antitoxins of various diseases trans- 
mitted to' the milk but also' the immunizing bodies, complements, 
alexins, agglutinins, opsonins, reductases, etc. Reductases some- 
times appear in milk as the result of bacterial contamination. More- 
over according to experiments by Woodhead, the opsonic indices of 
milk and whey were .72 and 1.02 respectively in tuberculous cows. 
This investigator believes that a high opsonic index of milk is of value 
in protecting children against tuberculosis. 

Bacterial Changes in Milk; Milk Poisoning. 

The occurrence of ptomains and leucomains has been most extensive- 
ly studied by Vaughan and Novy. These investigators have studied 
a number of cases of milk poisoning and have collected instances re- 
ported by others. In one case milk poisoning of a serious character 
was observed in the patrons of a milk route and gave much difficulty 
in the determination of its cause. The cows were well fed and cared 
for and the handling of the milk in most respects was quite satisfactory. 
It was observed, however, that the milk delivered at night was highly 
injurious while that delivered in the morning caused no bad. effects. 
Upon investigation it appeared that the dairyman was in the habit of 
milking the cows at noon and at midnight. The milk obtained at noon 
was placed in cans while still warm and thereupon, without any re- 
frigeration, was hauled a distance of about eight miles during the 
warmest part of the day. The milk thereby became somewhat unpal- 
atable and also developed highly dangerous ptomains which caused 
milk poisoning in the patrons of the milk route. 

In some of the individuals who suffered from milk poisoning the 
body temperature was as low as 94 degrees F. and in most instances 
was subnormal. At least one family was affected with a uniform set 
of symptoms in every case and all cases proved fatal. 

In another case of milk poisoning reported by Vaughan and Navy, 
the ptomain identified as tyrotoxicon developed in milk which was 
kept in one corner of the living rooms that had been transformed into 
a buttery. The woodwork of this room was moist and some of the 



4-7 

boards had rotted away, necessitating the placing of a second layer 
of boards over the original floor. A large mass of moist decomposing 
matter had accumulated between the two floors and emitted a peculiar 
nauseating odor. The milk which was kept in this place soon devel- 
oped tyrotoxicon and proved to be highly poisonous to all who con- 
sumed it, Kinnicutt succeeded in isolating tyrotoxicon from milk 
which had been kept in an unclean vessel. It appears therefore that 
this substance may develop under a variety of conditions. 

According to Vaughan and Novy tyrotoxicon may be obtained from 
filtered milk by neutralizing it with bicarbonate of soda and extracting 
with ether. 

Blythe has isolated from milk two alkaloidal substances which are 
considered to be leucoimuns and which are called galactin and lacto- 
chrome. No experiments have been made with these substances to de- 
termine their pathological effects. 

Milk Obtained During the Period op Heat. 

In studying the various factors which may influence the quality of 
milk, Doane has considered it of importance to note the effect of heat 
or estrum and has collected the results reported by the investiga- 
tions of others. In some cases during the period of heat the fat content 
has dropped as low as .7% and the milk curdled on being heated to 
the boiling point owing to the presence of an abnormal quantity of 
albumin. In another instance the content of protein and the acidity 
Avere found to be higher than in normal milk, while in still another 
oase the milk obtained during the period of heat proved to be unfit 
for manufacturing into cheese. 

During Doane's observations it appears that the milk showed an 
increase in fat content to the extent of one per cent during the second 
and third days of heat and that there was practically no variation in 
the other solids. In some cows no appreciable variation was exhibited 
in any of the milk constituents and none of the cows showed an abnor- 
mally low fat content. Doane concluded from his observations, there- 
fore, that at least so far as chemical anaylsis is concerned milk from 
cows during the period of heat is in a practically normal condition and 
suitable for consumption. Fascetti observed a slight increase in the 
percentages of fats, proteids and total solids in milk during estrum. 

Leucocytes in Milk. 

Many investigators have considered the presence of leucocytes in 
milk as an important matter in the determination of its fitness for 
use. Various attempts have been made to set up a normal standard 
for the leucocyte content of milk, but according to recent observations 
these attempts have not given very satisfactory results. It has gen- 
erally been assumed that a. direct connection exists between the presence 
of leucocytes in milk and pathogenic streptococci such as may cause 
contagious mammitis or other suppurative processes. ' 



48 

Eastes made an examination of 186 samples of milk from various 
parts of England with particular reference to a determination of the 
character of cells present in the milk as well as pathogenic micro- 
organisms. This investigator found, as have all others who studied 
this subject, that normal milk always contains leucocytes. During 
the first days of lactation colostrum corpuscles are present as well as 
leucocytes and the attempt has also been made to distinguish between 
leucocytes and pus cells. The distinguishing characteristics which 
have been set up as existing between these two kinds of cells, however, 
appear to be of little value in the light of recent investigations. Eastes 
found that the leucocytes are frequently associated with mucous 
threads and that the latter are nearly always accompanied by pus cells. 
Eastes came to the conclusion that mucous threads may usually bo 
considered as corroborative proof that the leucocytosis in such cases 
is due to some inflammatory lesion. The presence of an excess of 
Leucocytes and mucous threads was held to constitute muco-pus and to 
indicate lesions in the udder. In cases where the leucocytes were not 
accompanied by mucous threads, leucocytosis seemed to be connected 
with the presence of streptococci which appeared in nearly every 
sample of milk which contained pus and were rarely found in milk 
not thus polluted. Eastes believes that unboiled milk containing these 
streptococci is responsible for some of the cases of infantile diarrhea 
and mortality. 

One of the most elaborate investigations of leucocytes in milk was 
carried out by Doane at the Maryland Agricultural Experiment 
Station. In the attempt to define normal milk and to characterize 
the different variations in composition and condition which may con- 
stitute abnormal milk it was considered, desirable to study the occur- 
i-ence of leucocytes and if possible to determine the number which 
may be taken as a standard for normal milk and in general the condi- 
tions under which leucocytes appear to an abnormal extent. When- 
ever the milk of cows becomes stringy and contains hard lumps it is 
taken for granted that an inflammation is present in the udder. This 
condition of the milk may readily be noted by the milker and an 
investigation of the cause of the trouble should at once be made. In 
the meantime the milk should not be used for human food. A number 
of investigators, as already indicated, have studied the occurrence of 
leucocytes in milk but no unanimity of opinion has been reached 
regarding their importance in distinguishing between normal and 
abnormal milk. Doane working in co-operation with Buckley soon 
felt the need of a more accurate method of determining the number 
of leucocytes in samples of milk. For this purpose the most satis- 
factory instrument was found to be the blood counter used by physi- 
cians and veterinarians in diagnosing diseases in which the number 
of blood corpuscles is affected. The glass tube of the hemacytometer 
contains one ten-thousandth part of a cubic centimeter and may be 



49 

examined under the microscope with an objective sufficiently strong 
to permit the ready identification and counting of leucocytes. Ac- 
cording to the Doane-Buckley method 10 c. c. of milk are centrifuged 
for four minutes at a speed of 4,000 revolutions per minute. The 
fat is then removed with a cotton swab and the skim milk centrifuged 
again for one minute or more and the cream again removed. The 
reason for the removal of the fat is that the fat globules if present 
in the milk form a layer on the surface and interfere with the count- 
ing of the leucocytes. After centrifuging the milk a sediment will 
be found at the bottom of the tube amounting to as much as one c. c. 
in cows badly affected with garget. The milk above the sediment is 
removed with a small syphon using care to keep the point of the 
syphon near the surface of the milk so as not to agitate it. Two drops 
of a diluted alcoholic solution of methylene blue are then added and 
thoroughly mixed with the sediment, after' which the mixture is 
boiled for a few minutes for the purpose of intensifying the colora- 
tion of the leucocytes. Water is then added to the mixture to make 
the color of the liquid as a whole less intense. Some care must be 
exercised in transferring a drop of this stained liquid to the blood 
counter. After the glass tube of the counter is filled it is covered with 
a cover glass and; the leucocytes are allowed to settled to the bottom. 
In ordinary samples of milk the polynuclear leucocytes are present 
in largest, numbers together with a few small leucocytes with large 
nuclei. With a blood counter holding one ten-thousandth of a c.c. 
the amount of material added after treatment, according to the method 
just described, will be a proportion of the original 10 c.c. of the milk 
sample such that if the number of leucocytes found in the sample be 
multiplied by 1000 the resulting number will be the total number of 
leucocytes per c.c. of milk. Each square m.m. of the counting chamber 
is ruled off into 400 smaller squares of equal size to facilitate the ac- 
curacy and rapidity of the count. 

This method of determining the number of leucocytes is a simple 
one and has proved perhaps the most satisfactory and reliable of all 
those which have been proposed. In careful comparative tests with 
other methods it has given more satisfactory results in nearly all 
cases. 

In the opinion of Doane leucocytes are an indication of an inflamed 
condition of the udder, particularly if their number is large. Milk 
containing excessive numbers of leucocytes will therefore have to be 
considered as unfit for use, particularly in the case of infants. The 
ease with which leucocytes may escape from the blood or lymph into the 
milk has generally been recognized by dairy bacteriologists. In fact 
the udder is not the only gland into which leucocytes penetrate from 
the blood. Various other glandular structures and also the urine 
commonly contained leucocytes. Doane maintains,! however, that 
whenever there is an evident inflammation of the udder with evidence 



50 

of thick milk or hardening of one or more of the quarters there is 
always an abnormally large number of leucocytes. In all pus there 
is a large number of leucocytes and in fact pus cells and leucocytes are 
ciosely related if not identical structures. 

After it is admitted that a considerable variation is noted in the 
number of leucocytes present in milk, we still have the difficult matter 
of deciding the exact line of demarcation between normal and ab- 
normal milk in so far as the number of leucocytes is concerned. In 
many of the samples of milk examined by Doane and Buckley, mucous 
threads and fibrin were found as an evidence of inflammatory condi- 
tions of the udder. An effort was made to distinguish, if possible, 
between the leucocytes found in the milk as the result of inflammation 
and those which occurred in the blood of the same cow. The fibrin 
in bad cases of garget was apparent in the form of masses of threads 
which did not absorb the colors used for staining the leucocytes, 
rt was found possible, however, to stain the fibrin threads by means 
of carbol fuchsin. Fibrin was not always present in Doane's exam- 
inations in the samples of milk which contained a high leucocyte 
count. The fibrin appeared to cling closely to the glass of the counter 
tube and rendered it difficult to count the leucocytes. It was found 
possible, however, to absorb the fluid and the leucocytes by means of 
filter paper inserted at the bottom of the tube, while the fibrin for 
tiie most part remained at the top. This gave a means of separating 
the fibrin and readily identifying it. In staining the fibrin the best 
results were obtained from the use of Delaf eld's hematoxylin to which 
15% of carbolic acid had been added. With this stain the fibrin 
threads took on a dark blue or purple color within ten minutes. In 
applying this method for the identification of fibrin and the estima- 
tion of the number of leucocytes a number of observations were made 
on a cow with one hard quarter in the udder. At first the number of 
leucocvtes per c.c. was found to be 15,000,000 to 20,000,000 and 
some fibrin was present. After the leucocyte count had fallen to 
520,000 per c.c. the fibrin was found to have disappeared. In most 
cases fibrin was not to be demonstrated in the milk unless the leuco 
cyte count rose to 1,000,000 per c.c. Doane concludes therefore that 
the presence of 500,000 leucocytes per c.c. renders the milk suspicious 
and 1,000,000 per c.c. indicates an undoubted inflammation of the 
udder. 

Savage made a number of leucocyte counts in milk according to 
different methods including that of Doane. In examining these 
samples of milk streptococci were frequently found, in fact these 
organisms were demonstrated in 42% of the samples of milk. Since 
in these cases all of the cows were healthy the results are considered 
as showing clearly that streptococci as a class are very prevalent in 
milk. Leucocytes were present in every sample ranging in numbers! 
from 35 to 4380 per cubic m.m. in the milk from individual cows and 



51 

from 21 to 1980 in mixed milk. Savage's results indicate no connec- 
tion between the number of pus cells and streptococci. He states that 
he cannot differentiate between a leucocyte and a. pus cell and is not 
prepared to establish an arbitrary standard as to what number of 
leucocytes in milk shall be held as indicating the presence of pus. 

In a study of leucocytes in milk by Russell, these cells were found 
to the extent of more than 1,000,000 per c.c. in 3% of cows and more 
than 500,000 per c.c. in 10% of cows. The high numbers were fre- 
quently found in milk from perfectly healthy cows. It is considered 
by this investigator, therefore, that the matter needs more study before 
an arbitrary leucocyte standard is possible. Similarly Harris has 
found it impossible to lay down hard and fast rules regarding the 
importance of leucocytes. Harris believes that pus cells and leucocytes 
are identical structures. In his opinion leucocytes in milk up to a 
certain number are physiological but beyond that pathological. The 
line between these two conditions is an arbitrary one. It is suggested 
therefore that leucocytosis needs more study. Perhaps the signifi- 
cance of the pus cell in milk has been overrated. At any rate a 
veterinary inspection of the udders and less dependence on a mere 
examination of the milk for leucocytes will give more reliable results. 
According to a recent study by Ward we are not yet in a position to 
establish a leucocyte standard for milk. 

Dirt iist Milk. 

In the process of milking and the subsequent handling of milk 
opportunity is offered for dust, manure, sand and: other kinds of filth 
to fall into the milk. The amount of such foreign material contained 
in milk will obviously vary according to the carefulness with which 
the milk is drawn and handled. Under the most satisfactory condi- 
tions a certain amount of dirt gains entrance to the milk and when no 
special effort is made to keep the cows clean or to exclude dirt from 
the milk the amount of filth which gets into the milk is sufficient in 
some cases to render it disgusting. Some of the determinations which 
have been made by different investigators of the amount of dirt in 
milk have been collected by Kober. Every milk consumer has observed 
the presence of milk sediments which appear after the milk has been 
allowed to stand. This occurrence is so common that it is sometimes 
considered one of the natural features of milk. It has frequently been 
pointed out, however, that these milk sediments are largely made up of 
the manure of cows and other almost equally filthy and disgusting 
substances. Determinations of the amounts of filth in milk in various 
cities in Germany indicate that the quantity varies from 3.8 m.g. to 
12 m.g per liter. In some samples of milk collected in the City of 
Washington and studied for the purpose of determining the amount 
of filth present, as much as 180 m.g. were found per quart of milk. 

All materials which are commonly grouped together under the head 



52 

of dirt in milk must be considered as abnormal additions to the milk. 
The manure and dust from stables invariably carry large numbers of 
bacteria which cause not only active fermentation in the milk but 
produce disagreeable flavors and in some cases dangerous products. 
Various filter methods have been devised for the determination of 
the amount of dirt in milk, but these methods need not be described 
in detail in this connection. For the most part these methods involved 
running the milk through a centrifugal apparatus so as to throw the 
sediment in the bottom of the tube, after which the sediment is collected 
upon an asbestos filter, dried, and the total amount present in the 
milk is estimated from the dry weight of the filth thus collected. In 
a comparison of the- amount of dirt present in cream, new milk, gravity 
skim milk and centrifugal skim milk, in Norway, it was found that 
the amount of filth per liter averaged 1.5 m.g. in cream, 2.6 m.g. in 
new milk, 2.1 m.g. in gravity skim milk and .3 m.g. in centrifugal 
skim milk. 

Adulteration of Milk. 

The usual methods of adulterating milk consist in the partial 
removal of the cream and the addition of water, together with the use 
of various foreign substances for preventing the detection of the bluish 
color which would thus appear in milk, or various drugs for the pre- 
vention of fermentation in milk, or for the neutralization of the 
acidity after souring has actually begun. The adulterants which have 
actually been used in milk include water, aniline dies, annatto, soda, 
borax, boric acid, salicycil acid, formaldehyde, flour, arrowroot, farina, 
chalk, gypsum, tragacanth, magnesium carbonate, caramel, decoctions 
of bran, barley, rice, etc. 

The addition of water for the removal of cream lowers the nutritive 
value of the milk. If the cream is removed with care the milk may 
not thereby become contaminated. If water is added to the milk, 
however, contamination is likely to occur unless the water is abso- 
lutely pure. Moreover an individual who would deliberately water 
the milk intended for his customers would probably not suffer any 
compunctions of conscience regarding the quality of the water which 
he uses for adulterating his milk. A number of instances have been 
reported in which typhoid fever was caused by adulterating milk with 
contaminated water. The matter of the use of preservatives in milk 
will be discussed in chapter X. On account of the fact that milk is 
obtained twice daily there is little excuse for the use of any preserva- 
tives in it. Even where the milk must be shipped 300 to 100 miles 
to cities the application of refrigeration renders the use of preserva- 
tives quite unnecessary and inexcusable. The addition of coloring 
matters to milk is equally unnecessary. The whole milk of healthy 
cows fed on suitable rations such as the up-to-date dairyman should 
know possesses a satisfactory color without any manipulation. 



53 



CHAPTER III. 

HYGIENE AND DISEASES OF COWS. 

The great importance of giving careful attention to the health of 
cows should be obvious to all dairymen. Cows are kept for milk pro- 
duction for 10 to 12 years ior even longer, while beef cattle are 
marketed at the age of l 1 /^ to 3 years. The liability to disease is, 
therefore, much greater in the case of dairy cows on account of their 
long life if for no other reason. Moreover, milch cows are usually 
kept closely confined and are thereby subjected to many artificial 
conditions which may become a. source of danger if reasonable sani- 
tary requirements are not complied with. It should also be remem- 
bered that the period of lactation has been extended so as to be almost 
continuous from one calving to another and the milk yield has been 
greatly increased by breeding and selection with these definite objects 
in view. This large production of milk for so long a period puts 
severe demands upon the vital energies of the cow. 

In order to meet these great demands it is necessary to give attention 
to all details of care and management which may in any way affect 
the health of the animals, for any diseased condition in the cow may 
not only endanger the life of the animal and the health of the con- 
sumers of the milk but also leads to a diminution in the milk yield. 

Exercise. 

Attention may be properly called, in the first place, to the influence 
of exercise upon the health of cows. During the summer months 
nearly all dairy cows have more freedom than in winter and for the 
most part the exercise thus secured is quite sufficient for the preserva- 
tion of their health in a vigorous condition. In winter, however, it 
is necessary to house the cattle more closely and the problem of secur- 
ing exercise under proper sanitary conditions is somewhat more diffi- 
cult. Nearly all practical dairymen and veterinarians are agreed 
that a certain amount of exercise is necessary for reasons of health. 
The exact amount required will naturally vary somewhat according to 
the conditions which prevail about the premises. Exercise should not 
be given under conditions in which the animals are unduly exposed 
to storms or the inclemency of the winter weather. For milch cows 
it is probably best to be given in the form of the freedom of covered 
sheds or dry yards in which the animals have access to sheds. Advan- 
tage may and should be taken of this period of exercise to clean out 
the stalls in which the cattle are confined during the rest of the day, in 
order to keep then} in a, sanitary condition. 



54 



Grooming. 



Considerable importance attaches to the grooming of all animals and 
perhaps especially of dairy cows. The maintenance of the skin in a 
eiean and healthy condition is not only desirable in order to avoid 
contamination of milk with filth and bacteria during the process of 
milking but also on account of the direct relation between a healthy 
condition of the skin and the active performance of digestive func- 
tions as well as a general feeling of bodily comfort, It has been shown 
by experiment, that the process of digestion may be stimulated by 
cleansing and rubbing the skin. A further advantage of still greater 
importance consists in the fact that when the skin of cattle is properly 
cleaned and groomed it reacts more promptly to temperature changes 
and thus more effectively protects the animal against various forms 
of congestion and inflammation clue to colds. The methods of groom- 
ing need hardly be discussed. By the vigorous use of brushes and 
combs, which may be obtained anywhere of dealers in such articles, 
or even by the use of wisps of hay or straw, the greater part of the 
loose dust and filth may be removed. In some instances, it may be 
necessary to use soap and warm water to remove filth which adheres to 
the skin more firmly. 

Regularity in Care. 

Perhaps in the case of no domestic animal is the importance of 
regularity and care in feeding greater than in the milch cow. It is 
not only necessary that the rations should be of proper size and fed 
at suitable intervals but that the materials composing the rations 
should be chosen so as to constitute a balanced, ration. Materials to 
be chosen for this purpose will, of course, vary considerably according 
to the locality and only a few general suggestions can be properly made 
in this connection. The most successful rations, both from a stand- 
point of milk production and of the preservation of milk, include suit- 
able quantities of roots, silage, soiling crops, or pasturage in addition 
to hay and grain. Silage may be fed in rations of 40 to 60 lbs. per 
day with the addition of 8 to 10 lbs. of hay, and grain rations of 2 
to 12 lbs. depending upon the character of the grain and the individ- 
uality of the cows but usually in rations not to exceed S lbs. 

Feeding. 

The quality of all of these food materials should be the best. Moldy 
hay and rusty or smutty straw may not only be a source of contam- 
ination to the milk but also produce occasionally more or less serious 
diseases including various forms of digestive disturbances and pneu- 
monia. Under certain conditions, for reasons which are not well 
understood, smutty corn or grain may be fed in large quantities with- 
out producing any harmful results. It is never desirable, however, 
to take chances with such forage since at times serious losses are en- 



00 

countered from this cause. In one instance in Montana, one-half of 
a large dairy herd died within a few hours after being fed on smutty 
oat-hay. Similar statements may be made concerning moldy or smutty 
grain. Not only may such material cause acute indigestion with 
bloating and death in some cases but the lungs of the cattle may be 
affected by the germination of the spores inhaled from such material, 
and disagreeable odors may be communicated to the milk. 

The question of the times for feeding and the intervals between 
feeding periods may best be left to the individual dairymen to be 
settled according to the exigencies of each case. It has been shown, 
however, that regularity in the time of feeding is of great importance 
not only in its influence upon the milk yield but upon the contented- 
ness and consequently upon the health of the cattle. Since dairy cattle 
are of comparatively nervous disposition, it is obviously desirable that 
ail precautions be taken to prevent any unnecessary worry or excite- 
ment on their part. It is good practice, therefore, to feed the cattle 
at, as nearly as possible, precisely the same time each day in order 
that the cows may learn when to expect their rations. 

One of the most important factors in the successful feeding of dairy 
cows is to maintain the appetite and digestion in an unimpaired condi- 
tion. For this purpose it is necessary to make suitable changes from 
time to time in which attention should be given to substitutions such 
as will satisfy the requirements of a properly balanced ration and pre- 
vent sudden changes in the character of the ration as a whole. Sudden 
changes in the ration are easily avoided in summer and in winter. 
The most striking alteration in the character of the ration takes place 
in the spring and fall when the change occurs from the stable feeding 
to pasture or vice versa. At these times it is desirable to make the 
change as gradual as possible by feeding a little hay along with the 
pasture grasses or other succulent food. 

Bedding. 

Since the maintenance of the proper sanitary condition of stables 
requires that the floors be made of hard impervious material, it is 
necessarv to furnish the cows with a suitable litter or bedding both for 
warmth and comfort. Even the bedding should be selected with 
reference to suitability for such purposes. It should not consist of 
dusty, filthy material or of rusty or smutty straw. The same argu- 
ments are in force against the use of such material for bedding as 
in the case of feeds. The dust arising from smutty or filthy bedding 
may contaminate milk and may be a source of danger in the production 
of luno- diseases. Suitable bedding material mav be found in clean 
straw of cereals or in sawdust, shavings, and similar materials. 

Water. 

The water may become a factor in the production of disease in ani- 
mals by reason of the impurities which it may carry or when used 



56 

either in deficient or excessive quantities. Impure or contaminated 
water may contain low forms of vegetable and animal life including 
alg£e, fungi, bacteria, and protozoa and other animal species. All 
of these organisms of animal and vegetable nature may be present in 
either a living or dead condition. Various animal and vegetable 
substances may be carried by water in the form of sewage or other 
filth. Water naturally holds in solution a considerable variety of 
mineral salts which add to its nutritive value and palatability. Under 
certain conditions harmful mineral substances may be carried in the 
drinking water. 

A deficient amount of water may diminish the amount of the 
excretion from the skin and the kidneys and may cause impactions in 
the digestive canal of cattle. A considerable quantity of water is 
absolutely necessary for the proper performance of the functions of 
the kidneys and the digestive organs. Water in moderate quantities 
has been found in recent experiments to stimulate slightly the forma- 
tion of the digestive juices and may thus actually aid, to a certain 
extent, the ordinary process of digestion. An excessive amount, 
however, may diminish the digestibility of feeding stuffs and thus 
lead to an increase in tissue waste and to certain forms of indigestion. 

The health of cows may best be preserved in so far as the water is 
concerned by furnishing an abundant supply of fresh, pure water 
always accessible to the cows. Cows may be expected to drink from 
40 to 100 lbs. of water per day according to the ration consumed. The 
effect of varying quantities of water upon the bodily comfort of cows 
is indicated by the fact that more milk is given and the cows appear 
less uneasy when allowed to drink at will than when watered only at 
intervals of considerable length. Wherever a constant supply of water 
is maintained, however, particular attention must be given to pre- 
venting its contamination with bacteria and various kinds of dust and 
other filth. The supply of water for drinking purposes on farms is 
very different on different farms. In some instances, water is obtained 
from running streams, while in others it comes from springs, cisterns, 
or wells. The relation of water to animal disease is, perhaps, more 
intimate than is usually supposed. Recently much attention has been 
devoted to the protection of the water supply of cities but as a rule 
efforts in this direction have been confined to the purification of water 
for human use. At the same time the opinion prevails too widely 
that water may be quite unfit for human use and still good enough 
for animals. An examination of water from different sources at the 
Indiana Experiment Station showed that its content of bacteria may 
vary enormously. The number of bacteria per cubic centimeter varied 
from 4 in tubular wells 60 to 150 ft. deep to 2,680,000 in a hog 
wallow. The water obtained from clean stock troughs, tile drains, 
and cisterns was comparatively free from bacteria. The same may 
be said for river water except in the immediate vicinity of cities. 



01 

Wells which receive surface drainage were found to contain very 
impure water and the same condition was observed in stock troughs 
not properly cared for. The soil acts as an effective filter upon bac- 
teria which may come in contact with it. Experiments have shown 
that only a small per cent of bacteria pass through the first inch of 
soil, while nearly all of the disease producing bacteria, are destroyed 
by filtering through a few feet of soil. In examinations of different 
strata of soil by the Indiana Experiment Station it was found that 
the number of bacteria varies from 2,800 at a depth of 54 in. to 
518,400 at the surface. The number of bacteria 1 in. underneath 
the surface is found to be 51,200 under similar conditions. This 
shows the effective filtering action of the soil and indicates that the 
great majority of bacteria are contained in the first inch of the soil. 
The relative proportions of bacteria at different depths were quite 
similar before and after rain storms, being somewhat greater, how- 
ever, after showers. As a rule, the bacteria found in water are 
not injurious and do not cause specific diseases. Whenever bacteria 
are present in large numbers, however, this fact may be taken as an 
indication of the presence of considerable organic material in the 
water and consequently of its unwholesomeness. Water may readily 
carry the bacterial organisms of blackleg, anthrax, and certain other 
diseases which affect cattle, as well as typhoid and other human 
diseases. 

The protection of the water supply on farms is ordinarily a simple 
matter. It is necessary to prevent the undue contamination of the 
water with the feces of animals and it is also obviously desirable that 
hogs and other animals should not be allowed to stand in the water 
supply which may be used for cows or other domestic animals. In 
addition to bacterial diseases, liver flukes, which cause serious in- 
festations in calves, and lung and stomach worms are largely conveyed 
by an impure water supply and the vegetation growing along the 
border of contaminated pools or streams. 

It is evident from this discussion that the water supply is as im- 
portant in the sanitation of domestic animals as in the preservation 
of human health. Water should not only look clear but should not 
possess disagreeable odor or flavor. Wherever any contamination is 
suspected it is a comparatively simple matter to make tests for the 
determination of certain substances which indicate the presence of 
contamination. In order to determine whether nitrites are present it 
is merely necessary to take 50 cc. of water and add 1 cc. each of 
dilute hydrochloric acid, potassium iodid solution, and a starch solu- 
tion. The development of a blue color indicates the presence of 
nitrites. If no blue color develops within 2 minutes it may be assumed 
that no nitrites are present. In testing for nitrates take 50 cc. of the 
water to be examined and add 1 cc. of dilute sulphuric acid (1 part 
in four), 1 cc. of starch solution, and a minute crystal of potassium 



58 

iodid. If no nitrites appear to be present add a few milligrams of 
zinc dust previously mixed in distilled water. A blue color will appear 
if nitrates are present. A simple test, for ammonia in water may be 
made as follows: Take 50 cc. of the water to be examined and add 
to it 2 cc. of a concentrated ammonia-free soda solution. After the 
precipitate has settled the clear fluid above is treated with 1 to 2 cc. 
of Nessler's reagent, A yellowish coloration or a yellowish-red pre- 
cipitate (mercuric ammonium iodid) indicates the presence of am- 
monia, Lead in water may be detected by adding acetic acid and 
hydrogen sulphid. In the presence of sulphur a black precipitate is 
formed which may be redissolved in nitric acid, then the addition of 
a dilute solution of sulphuric acid produces a white precipitate which 
turns black when hydrogen sulphid is added. In testing water' for 
copper the sample may be rendered slightly acid by the addition of 
acetic acid after which hydrogen sulphid produces a black precipitate. 
If this precipitate is dissolved in nitric acid and the diluted solution 
then treated with ferrocyanid of potash gives a brownish-red. precipi- 
tate of ferrocyanid of copper. 

The bacteriological methods used in the examination of milk are 
also applicable for the examination of water which is suspected of 
being contaminated with pathogenic organisms. These methods are 
described in another place. It is perhaps even of greater importance 
that scrupulous care should be exercised in the protection of the water 
supply than in case of food supply since bacterial infection may be 
carried in the drinking water to the cows and in the water used for 
washing purposes to the milk cans and other utensils. The bacterial 
contamination of water is almost certain to take place sooner or later in 
unprotected wells which are located too close to stables or other sources 
of filth so as to receive surf a ^ drainage. Th^ importance of the pro- 
tection of the water supply becomes more apparent when attention is 
called to the considerable length of time during which pathogenic 
bacteria may live in water. To be sure, most disease-producing bac- 
teria gradually lose their virulence in water under the influence of 
dilution and the action of harmless bacteria. According to Boucher 
the typhoid bacillus retains its virulence in water not longer than 
48 hours. Experiments carried out by Kasparek, however, show that 
the bacilli of hemorrhagic septicemia, of cattle may live in water for 
61 days, the virus of foot-and-mouth disease for 19 days, anthrax 
spores for li/o years, anthrax bacilli for 8 days, tubercle bacilli for 
5*4 months, tetanus bacilli for 15 months, rabies virus for 17 days, 
and cowpox virus for 5 months. It has also been shown by experiment 
that the tetanus bacilli may remain virulent in dry pus and other 
animal material for 16 months. In dry sputum and tuberculous pus 
the tubercle bacilli remain alive but not very virulent for about 7 
months even under the influence of diffuse sun light. Anthrax ba- 
cilli retain their virulence in dried blood for about 2 months, in an 



59 

almost isolated condition at a- temperature of 16 to 22 °C. in sun 
iight for 18 days and under similar conditions at a temperature of 
33 °C. for 12 days. Blackleg bacilli have been shown to retain their 
virulence in dead muscle for 6 months. These data are presented in 
this connection on account of their importance in the possible trans- 
mission of infectious diseases through the medium of water. It is 
obvious that animal carcasses or parts of dead bodies containing 
pathogenic bacteria may be left in exposed situations for months and 
may be washed away in water and become distintegrated so that the 
disease-producing bacteria gain entrance to the water supply for 
domestic animals. The only way to protect the water supply suc- 
cessfully, therefore, is to observe scrupulously all the requirements of 
cleanliness and sanitation. 

Salt. 

Cows require a certain amount of salt in order to remain in health 
and in order that the physiological processes of digestion and milk se- 
cretion may actively continue. The effects of the deprivation of salt 
are usually referred to under the term salt hunger and may become 
quite serious if salt is withheld for long periods. Some of the most 
striking instances of salt hunger are observable in the arid regions of 
the western States where cattle are forced to eat alkali on account of 
not being supplied with salt. The common forms of alkali are car- 
bonate of soda and sulphate of soda and can not be supposed to replace 
salt in the physiology of animals. 

Disinfection. 

By the strict observance of all precautionary measures outbreaks 
of infectious diseases among cattle may be reduced to a minimum. 
Such outbreaks, however, can not be entirely prevented and this fact 
makes it necessary to discuss a general plan of disinfection for the 
purpose of checking the spread of infectious diseases after an out- 
break has occurred. The problem of disinfection after the occurrence 
of animal diseases is a much more difficult one than in the case of dis- 
infection of human dwellings. In the first place, stables are usually 
not built of materials which lend themselves so readily to disinfection, 
they are constructed more loosely and this fact largely prevents the 
effective use of gaseous substances for destroying bacteria. 

After the occurrence of an infectious disease it is necessary to dis- 
infect all utensils, instruments, equipment, or materials of any kind 
which have come in immediate contact with the diseased cows. All 
bedding, rubbish and filth in the stables should be removed and 
burned. Mangers should be thoroughly cleaned and washed by scrub- 
bing with an antiseptic solution such as 4 per cent of formalin, 5 per 
cent carbolic acid, or 5 per cent lysol. Corrosive sublimate, 1 part to 
1,000 in water may be used on wood work and all other material except 



CO 

metals. Small instruments and other . articles which, lend themselves 
readily to such treatment may be boiled. Creolin at the rate of 1 
part to 50 parts od: water may be substituted for any of the disinfect- 
ants just mentioned. In all disinfectant operations it should be re- 
membered that direct sun light is one of the best natural agents in 
the destruction of bacteria, and special efforts should be made to 
secure its thorough admission to all possible parts of the stable to- 
gether with good ventilation. No contaminated material or carcasses 
of animals dead of infectious diseases should be buried shallow in the 
ground or be placed so that drainage may occur from this material 
into the water supply. It should be remembered that dogs, cats, 
crows, turkey buzzards, and other animals may feed upon such ma- 
terial and thus serve to spread infection to an uncontrollable extent. 
In the vicinity of large abattoirs or wherever digesters have been 
established for the utilization of animal carcasses it is possible to 
obtain some return for such material. By means of digesters and 
similar apparatus animal carcasses are rendered absolutely harmless 
and at the same time fat, gelatin, and fertilizers are obtained from 
the material. In country districts the best methods of disposing of 
animal carcasses are burying to a depth of from 4 to 6 feet or burn- 
ing. If carcasses are to be buried they should be covered with quick 
lime or sprinkled with chlorid of lime. Burying is perhaps necessary 
in many localities where the supply of fuel is scanty or where burning 
would, be an expensive process. Extensive experience was recently 
had along this line by the Bureau of Animal Industry in the eradica- 
tion of foot-and-mouth disease among dairy cows and other cattle. In 
the work of the Bureau both burying and burning were employed in 
destroying carcasses of diseased cattle. The cost of burning dead 
animals and the applicability of the method was recently studied by 
McDowell of the Nevada Experiment Station. It was found possible 
to destroy animal carcasses at a reasonable expense by the use of sage 
brush, refuse wood, or brush trimmed from trees with the addition of 
kerosene oil to hasten or complete the destruction of the carcass. The 
amount of oil required varied from 2% to 5 gal. and the total expense 
for material and hire of a man varied from $1.56 to $5.87 per animal. 
Lt is probable that the cost of the operation could be considerably 
reduced by the establishment of neighborhood organizations for this 
purpose. Pieces of railroad rails or other similar iron bars may be 
conveniently placed for supporting the animal carcass and a trench 
may be dug underneath the iron bars in which crude oil or other 
materials may be burned for incinerating the carcass. In removing 
animal carcasses for burying or burning no chances should be taken 
of spreading the disease by dragging the animal on the ground. It 
is better to construct a cheap "mud boat" on which the animal may 
be hauled and which may be burned together with the carcass. It 
scarcely needs mention that cows dead of dangerous infectious diseases 
such as anthrax and foot-and-mouth disease should, not be skinned. 



61 

After a preliminary cleaning of stables there are several methods 
from which a choice may be made for bringing about complete disin- 
fection. All exposed parts of the stable may be covered with a thick 
white wash or with milk of chloric! of lime. A 4-per cent solution of 
formalin may be added to the white wash to increase its effectiveness. 
One objection to the use of chlorid of lime consists in the fact that the 
odor of this substance may be perceptible in the milk long after its 
application to the walls and ceiling of the stables. Whatever anti- 
septic is used it should be applied thoroughly to the mangers, floors, 
stalls, ceiling, and walls so as to thoroughly disinfect all parts exposed 
to the contagious material. In some instances it may be convenient 
to use boiling water or direct live steam in disinfecting the stables. Tf 
these methods are adopted care should be taken to be sure that the 
water is at a boiling temperature when it comes in contact with the 
surfaces to be disinfected, otherwise pathogenic bacteria will not be 
destroyed. These methods are under the best conditions less effective 
than the use of chemical disinfectants. Carbolic acid in a 5-per cent 
solution is reasonably certain to destroy all sources of contagion but 
is open to the objection that it may taint the milk with its disagreeable 
odor. Cresol in 5-per cent solution in water has also given excellent 
results in disinfecting stables. Direct dry heat may be applied to walls 
by means of a blast lamp such as is used by plumbers. By means of 
this apparatus a sufficient temperature may be quickly produced on the 
surface of walls and stalls to destroy any bacteria which may be 
present. 

Formalin in a 4 or 5-per cent solution in water is one of the most 
efficient disinfectants for use in stables. It may be used on all mater- 
ials including metals and does not cause corrosion. It is volatile and, 
therefore, the odor remains about the stable for only a, short time. 
During the application of formalin either in a fluid or gaseous form, 
the fumes cause considerable irritation in the eyes and respiratory 
passages of the workmen. Formaldehyde fumes are less applicable for 
use in stables than human dwellings. The fumes do not penetrate 
very rapidly and. it is quite necessary that the stable be rendered as 
nearly air-tight as possible in order that the fumes may have their 
effect. This, however, is practically impossible in most stables since 
the quarters in which the cows are confined usually communicate with 
the hay mows arid other parts of the barn. Where the contaminated 
part of the stable can be tightly closed, however, formalin brings about 
a rapid disinfection of all exposed surfaces. As already indicated, 
however, it is necessary that straw and filth be removed and cracks 
be filled up in order to allow the formalin fumes to come directly in 
contact with all bacteria. In the application of formalin or other 
chemical disinfectants it should be remembered that the action of 
these substances is more effective when a moderately high temperature 
is maintained in the stables. One of the great, advantages of for- 
malin consists in the fact that it is a true deodorant. It does not con- 



62 

ceal one odor by emitting another but unites with the albuminous 
matter in feces and other materials about the stable to form new 
chemical compounds which are odorless and sterile. 

Potassium permangenate is a disinfectant of great power but its 
application is quite limited on account of the fact that it is readily 
rendered inert by coming in contact with organic material. Its chief 
use is in the purification of water. Wells or cisterns which are be- 
lieved to have become contaminated with pathogenic bacteria may be 
disinfected by the use of merely a sufficient quantity of permangenate 
to give a slight tinge of color to the water. Cows appear not to be 
harmed by drinking water containing minute quantities of potassium 
permanganate although no data are available regarding the possible 
cumulative effects of this substance. 

White wash or milk of lime is one of the commonest and most con- 
venient disinfectants for use on the farm. It is readily prepared by 
slaking lime in water and may be rapidly applied by means of the 
brush or spraying apparatus so as to reach all parts of the building 
which have been exposed to the infection. Quick lime is perhaps the 
best substance for disinfecting the excrement of cattle. The lime not 
only destroys the bacteria present in such substances but is of some 
value as a fertilizer when applied to the land,. 

Lysol is perhaps one of the least poisonous of the commonly used 
disinfectants. It may be used in 2 to 3-per cent solutions in the dis- 
infection of the reproductive organs of cows after the occurrence of 
contagious abortion. In the stronger solutions (4 to 5 per cent) it 
may be used in all cases where formalin would be recommended. It 
contains a. considerable percentage of formalin and is consequently of 
almost equal value with formalin as a deodorizer. A good disinfect- 
ant solution may be prepared by mixing carbolic acid and sulphuric 
acid at the rate of 1 lb. each of the acid in 5 gal. of water. The vessel 
containing the carbolic acid should be placed in cold water and the 
sulphuric acid should be added slowly on account of the fact that 
much heat is developed in the mixing. The mixture is then added to 
5 gal. of water immediately before use. This material is effective and 
quite cheap. 

In outbreaks of disease where stables are badly infested with in- 
sects and where the possibility of their carrying disease must be ad- 
mitted it is desirable to fumigate with sulphur fumes or hydrocyanic- 
acid gas for the destruction of these pests. Both sulphur dioxid and 
hydrocyanic-acid gas are effective in destroying pathogenic bacteria 
as well as insects. In estimating the amount of sulphur necessary for 
use in a given case it should be remembered that 1 lb. of sulphur 
burned in 1,000 cu. ft. of space will produce an atmosphere of 1.15 
per cent sulphur dioxid. Commercial sulj^hur contains certain im- 
purities, however, so that 1 lb. may be depended on to produce only 
a 1-per cent mixture of the gas in 1,000 cu. ft. of space. A 5-per cent 



63 

mixture is about what is necessary and therefore 5 lbs. of sulphur 
may be provided for each 1,000 cu. ft. The effectiveness of sulphur 
fumigation is lost if the stable is not tightly closed and the gas is less 
active at low temperatures than at moderately high ones. Sulphur 
dioxid is rapidly fatal to rats, mice, fleas, lice, mosquitoes, and other 
insects. 

Hydrocyanic-acid gas is extensively used in the disinfection of 
nursery stock and in the fumigating of orchard trees for insect pests. 
Its use has recently been extended to the destruction of insect pests in 
dwelling houses, stables, ships, railroad trains, etc. The gas is much 
more powerful as an insecticide than as a germicide but is effective 
against some of the less resistant pathogenic bacteria. Hydrocyanic- 
acid gas is generated by combining potassium cyanid, 1 part; sul- 
phuric acicl, 1.5 parts; and water 2.25 parts. The acid is diluted in 
water in a receptacle which is capable of enduring the heat produced 
by the chemical combination. After the acid has been diluted iu 
water the potassium cyanid is added and all openings in the stable 
must be tightly closed. It should be remembered that hydro-cyanic- 
acid gas is an exceedingly poisonous substance and causes death rapidly 
to large animals as well as to insects. It must, therefore, always be 
used with caution and rooms or stables which have been fumigated 
should be opened and allowed to ventilate an hour or more before it 
is safe to enter. In estimating the amount necessary for fumigation 
1 oz. of potassium cyanid and 1.5 of sulphuric acid are sufficient for 
each 100 cu. ft. of space to be fumigated. 

In the eradication of animal diseases, reliance must be placed on 
the thorough disinfection of stables and premises and the isolation of 
diseased animals. Healthy animals should not be allowed to enter 
infected stables until after the process of disinfection has been com- 
pleted. In some instances where the outbreak is of a serious nature 
and where the stable is old and of little value it may be cheapest in 
the long run to burn the whole stable and start anew. It is obvious 
that the most reasonable way of preventing the further spread of the 
disease to healthy cattle is to remove the healthy animals to fresh 
quarters and then inaugurate the system of combating the disease in 
infected stables. 

Where healthy cattle have been exposed to infection it may be 
desirable to take the precaution of disinfecting the skin. For this 
purpose a number of disinfectants may be used in such a. manner as 
to destroy the pathogenic bacteria without seriously injuring the hair 
or the skin of the animals. Among the suitable materials for use in 
this way, mention may be made of carbolic acid, 5 per cent ; potassium 
permangenate, 3 per cent; corrosive sublimate, 0.1 per cent; chloro- 
naphtholeum, 2.5 per cent; and lysol, 5 per cent. These substances 
may be applied with a brush or with a spraying apparatus and their 



64 

application should preferably be preceded by a thorough cleansing of 
the skin with soap and water. 

The Diseases of Cows. 

Among the numerous infectious and other diseases to which cows 
are susceptible we may discuss in this connection the more important 
ones from the standpoint of milk production and human health. On 
account of the practical difficulties involved in arranging these dis- 
eases satisfactorily according to their etiology or nature an alpha- 
betical arrangement has been adopted. 

Abortion. — This term is used to denote premature birth of off- 
spring. It may be due to various causes and is accordingly of a non- 
contagious or contagious character. Noncontagious abortion may be 
brought about by excessively cold weather ; frozen food ; cold storms ; 
blows and other mechanical injuries; moldy, smutty, and unwholesome 
food; fermentation of food and consequent bloating; confinement in 
poorly ventilated stables; ergot; irritating drugs; constitutional dis- 
eases; undue excitement or worrying with dogs; and from various 
other causes. These forms of abortion may be distinguished from 
the contagious form by the fact that the disease does not spread by 
contact like true contagious diseases but is clue to other causes such as 
have just been mentioned. Where several cases occur in the same herd 
it will be apparent upon investigation that all the aborting cows have 
been subjected to the same unfavorable conditions. For preventing 
these forms of abortion it is necessary that care be exercised in fur- 
nishing pure water of a moderate temperature, wholesome feeding 
stuffs free from smuts, molds, ergot, etc. and by providing stables with 
plenty of ventilation. Particular attention should be given to these 
matters during the first few weeks just prior to calving. 

Contagious abortion is due to the action of a bacillus or specific con- 
tagion which is distributed by means of breeding animals. Mere 
association in the same herd, does not transmit the disease, actual con- 
tact is necessary for such transmission. This disease recurs from year 
to year in the same cows if no treatment is adopted. In cases of 
the contagious form, abortion may take place during the first 2 or 3 
months of gestation and may thus escape detection unless particular 
attention is given to the subject. The best method of treating this 
disease consists in a thorough application of disinfectants to the cows, 
the fetus and the fetal membranes, and stables. For this purpose 
a 1 per cent solution of carbolic acid or a solution of corrosive sub- 
limate, 1 part in 1,000, may be used, as a vaginal wash. The fetus 
and fetal membranes should be burned or otherwise rendered innocu- 
ous. The hind legs and other parts of the cow which have become 
infected should be treated with antiseptic solutions. For the disin- 
fection of stables the methods previously recommended in discussing 
disinfection may be adopted. Cows appear to become immune to this 



65 

disease after aborting 2 or 3 times. It is desirable to quarantine 
young cows which have aborted until they become immune and to 
exercise great care in preventing the introduction of aborting animals 
into a herd which is free from the disease. 

Actinomycosis. — Actinomycosis is an infections disease character- 
ized by the development of tumors in various parts of the body espe- 
cially the head. The disease is also known as big jaw, lumpy jaw, 
and wooden tongue. The most recent investigations indicate that 
there are 3 forms of actinomycosis due to 3 distinct organisms but 
producing quite similar symptoms. As a rule, however, only 2 forms 
are recognized, viz., true actinomycosis and actinobacillosis. Actino- 
mycosis proper is due to infection with a fungus known as actinomyces 
which produces radiate clusters of fungus threads in different tissues 
of the body especially in the jaw bones and the tongue. The disease 
may also appear under the skin of various parts of the body, and in 
the pharynx, larynx, lungs, and digestive tract. The most character- 
istic forms of actinomycosis are those which are observed in the jaw 
bones in which large bone tumors are produced and in the tongue 
which becomes hardened as a result of the disease and gives rise to 
the name wooden tongue. . Actinomycosis of the lungs may some- 
times be mistaken for tuberculosis but may readily be distinguished 
by a bacterial examination which will disclose the presence of com- 
paratively large radiate clusters of organisms not seen in cases of 
tuberculosis. The method of infection is still somewhat uncertain 
although most observers believe that animals become infected with 
the food. Actinomyces or ray fungus may be found on various 
plants and it is probable that it gains entrance to the organism of 
cattle by means of punctures or abrasions of mucous surfaces due to 
sharp-pointed awns, seeds, or other fragments of vegetable tissue. The 
infection spreads very slowly and it is not certain that infection 
takes place directly except in the rarest instances. It seems more 
probable that the fungus contaminates grasses and other forage plants 
and thus gains entrance to other healthy cattle. Actinomycosis oc- 
curs in man and appears to be identical with the disease observed in 
cattle. The transmission of actinomycosis to man. through the con- 
sumption of the meat or milk of the diseased animals has not been 
definitely demonstrated but it must be admitted that such transmis- 
sion may take place in rare instances particularly if the mucous mem- 
brane of man be weakened by the presence of any disease. In man, as 
in other animals, the disease appears to arise from some part of the 
alimentary tract. Decaying teeth are often the point of entrance of 
the organism. 

Actinobacillosis has been reported from South America, Canada, 
and various parts of the United States. The symptoms of this disease 
are almost identical with those of actinomycosis proper. A micro- 
scopic study of diseased tissue, however, shows the presence of an 



66 

actinobacillus. In this form of the disease as in actinomycosis proper 
the head is chiefly affected particularly the jaw bones. 

Anthrax. — This is an infectious disease due to infection with an- 
thrax bacillus and is also known by the names charbon, splenic fever, 
wool sorter's disease, malignant pustule, etc. It occurs in nearly all 
warm-blooded animals including man and is distributed throughout 
the known world. Herbivorous animals are apparently most suscept- 
ible. Infection from anthrax may take place through the digestive 
tract, the skin, or lungs. In cattle infection is most frequent through 
the digestive tract. The disease appears suddenly with high temper- 
ature, carbuncles, edema of the skin, difficult breathing, and cerebral 
manifestations. During the progress of the disease hemorrhages of 
varying extent are produced in different parts of the body especially 
in the submucous, subcutaneous, and subserous tissues. The blood 
assumes a dark color and tar-like appearance. In acute form the 
disease usually terminates with fatal results within 2 or 3 days. The 
bodies of animals which have died of the disease bloat rapidly. An- 
thrax prevails most extensively in countries which are subject to 
periodical inundation or flooding from streams. Pools of stagnant 
water and rivers or small streams contaminated with waste material 
from tanneries may also carry infection. Contagion is also widely 
spread through the unburied bodies of dead animals by means of 
carrion birds and, other animals and incests. After an, outbreak of 
anthrax the stables must be thoroughly disinfected and all healthy 
cattle should be removed from fields which are likely to be infected. 
Tn many localities the continued occurrence of the disease has been 
found to depend upon carelessness in allowing carcasses of dead ani- 
mals to remain unburned and unburied. Little benefit is derived 
from medical treatment of this disease. The main reliance should be 
placed on vaccination which, in the hands of competent veterinarians, 
has yielded quite satisfactory results. Pasteur's method of vaccina- 
tion consists in the use of virus of 2 strengths both of which have been 
attenuated by being grown at a temperaure of 42 to 43 °C. for several 
days. The first vaccination is of low virus and the second is of some- 
what greater strength. Another method af vaccination consists in 
taking the blood from an animal just dead of anthrax, heating it to 
the boiling point, then dissolving it in water or bouillon and using it 
for injecting purposes. In man anthrax appears in the form of malig- 
nant pustules and is a very dangerous disease. It may be transmitted 
directly from infected tissues or by means of the milk of animals 
suffering from the disease. The anthrax bacillus, however, does not 
usually appear in the milk until the later stages of the disease. 

Blackleg. — This is also known as black-quarter, symptomatic 
anthrax, etc., and is an infectious disease which affects chiefly young 
cattle between 6 months and 2 years of age. In older animals the 
disease is much less frequent. Blackleg is a rapidly fatal disease and 



67 

was formerly confused with anthrax. It is produced, however, by a 
specific bacillus which may easily be distinguished from that of 
anthrax. Blackleg occurs as a stationary disease and is confined 
almost exclusively to blackleg districts. The period of incubation is 
about 2 days. The disease may affect cattle, goats, sheep, and horses 
but is not transmissible to man or hogs. The most important means 
of diagnosing this disease especially of distinguishing between black- 
leg, tumors appear under the skin which emit a crackling sound on 
friction and contain gas. These tumors are most frequently located 
on the thigh, neck, shoulder, and lower part of the breast. In dis- 
tinguishing between anthrax and blackleg it should be remembered 
that in anthrax the spleen becomes greatly enlarged and the blood is 
not readily coagulable. Anthrax swellings differ from those which 
occur in blackleg in not containing gas and in causing death less rap- 
idly. Malignant edema closely resembles blackleg the swellings in 
both diseases containing gases. In general, however, malignant 
edema arises from a wound of considerable size, while blackleg ap- 
pears to develop as the result of infection through minute punctures 
or skin wounds of such small size as not to be readily detected. Black- 
leg may be successfully combated by preventive vaccination. The 
Bureau of Animal Industry and various experiment stations have 
perfected a system of vaccination and have distributed vaccine so ex- 
tensively that the disease is now well under control and reliable 
statistics regarding: the effectiveness of vaccination are now available. 
During the past 7 years nearly 8,000,000,000 doses of vaccine have 
been distributed by the Bureau of Animal Industry and the statistics 
collected indicate that the losses after vaccination are reduced to less 
than 1 per cent. 

Bloating. — Bloating is also commonly referred to as tympanites, 
hoven, or bloat. It is of especially frequent occurrence in cows after 
eating large quantities of feeding stuffs which readily ferment. The 
disease is characterized by intense swelling of the left side and is due 
to the formation of gases of fermentation in the paunch. It may be 
due to eating any kind of feed which causes indigestion or fermenta- 
tion. When cattle are first turned on pasture of green clover or 
alfalfa serious cases frequently result until the animals become used 
to this kind of forage. Bloating may be brought about by eating too 
hastily as well as by eating too much or too readily fermentable food. 
Quite frequently the quality of the food is the cause of bloating. 
Frozen roots or clover wet with dew or frost are generally regarded 
as dangerous. As a rule, the clovers and alfalfa produce bloating 
only when eaten in a green condition. A few cases have been observed, 
however, from eating these plants in the form of hay. Whatever 
may be the cause of excessive bloating from the use of green legum- 
inous forage it is certain that cattle may become accustomed to eating 
these plants in a green state so that no bad effects are obtained from 



68 

feeding upon it. It may probably be wise at first to allow the cows 
to remain only for a short time upon such pasture until the clanger of 
bloating is passed. 

When bloating is not too far advanced a sufficient treatment may 
be found in keeping the animal moving for a short time. Where 
cows are not observed, however, until the paunch is firmly distended 
it is necessary to adopt some more efficient remedy. Large doses of 
melted lard, solutions of soda, and other alkaline substances some- 
times bring about prompt relief but in many instances the stomach 
may be so distended that puncture or rumenotomy may be necessary. 
This is almost always necessary if the production of gas has gone so 
far that the animal is unable to walk. Under such conditions, the 
distention of the paunch may become so great as to interfere with res- 
piration or the action of the heart or even so far as a rupture of the 
diaphragm or intestinal walls. In such cases it is necessary to make 
an incision on the left side of the body at a point about equidistant 
from the last rib, the angle of the hip bone, and the vertebral column. 
I he incision may be made with a broad-blade knife with one stroke, 
but more effectively with a trochar and canula which may be readily 
obtained from dealers in veterinary instruments. 

Cornstalk disease. — For many years reports have been received of 
losses in cattle from feeding in cornfields in various States of the 
central west especially Nebraska, Kansas, Missouri, Iowa, Illinois, 
etc. The conditions under which cases of this disease occur vary so 
extremely that great difficulty has been experienced in determining 
tne cause and nature of the disease. The disease usually appears sud- 
denly. The animal remains apart from the herd, the back is arched 
upward, and various nervous movements are observed.. Sometimes 
the animal kicks at the abdomen or gives other evidence of internal 
pains, the gait is uncertain and lameness and paralysis frequently 
appear before death. In general the course of the disease is from 24 
to 36 hours. As a rule, the organs have been found to be normal in 
post-mortem examinations made after death from this disease. Oc- 
casionally, however, hemorrhages are observed upon the coverings of 
the lungs, heart, and thoracic cavity. No line of treatment has been 
found satisfactory in controlling this disease. Investigations carried 
on by the ISTebraska Experiment Station show that the stomach con- 
tains no trace of active plant principles. It is, therefore, not likely 
that poisonous weeds found in the cornfield have anything to do with 
the disease. In some cases the stomachs of cows dead of the disease 
have shown abnormal amounts of chlorid of potash. In 1901, some 
of the cornstalks analyzed contained abnormally large amounts of 
potassium nitrate. In 1902, however, only traces of this substance 
were found. It is apparent from this brief account, therefore, that 
further investigations are necessary to determine whether there is any 



69 

relation between the presence of large of large quantities of potassium 
nitrate in cornstalks and the appearance of cornstalk disease. 

Recently there is a tendency among investigators to consider corn- 
stalk disease as identical with hemorrhagic septicemia. This position 
is taken by Moore, Law, Brimhall, and others who have studied hem- 
orrhagic septicemia in Minnesota and elsewhere. 

Cowpox. — Cowpox also known as variola of cattle is a contagious 
disease of cattle which is characterized by a fever, shrinkage in the 
milk yield, and by the appearance of pustules under the teats and 
udders of dairy cows. This disease, although of a contagious nature, 
is quite harmless so far as cattle are concerned and runs a benign 
course. It is most common in the eastern States. The contagion of 
cowpox is not spread except by actual contact. Apparently the virus 
cannot travel through the air. The disease quite frequently attacks 
horses, appearing upon the heels, lips, nostrils, and other parts of the 
skin. It may be readily transmitted from the horse to cattle or vice 
versa if the same attendant grooms both cattle and horses. The dis- 
ease is usually transmitted from one cow to another by milkers who 
do not cleanse or sterilize their hands after milking an animal affected 
with cowpox. It has long been known that cowpox may be transmitted 
to man through wounds or elsewhere and that the mild disease thus 
produced confers immunity to smallpox. Investigations thus far 
conducted with reference to the relationship of these diseases indicates 
that smallpox and cowpox are specifically distinct. Young cows are 
most susceptible to cowpox but older animals are not immune. The 
period of incubation varies from 4 to 7 days. At first a slight eleva- 
tion of temperature occurs and this is followed by the appearance of 
an inflamed abscess upon the teats, udder, and under the inner surface 
of the thighs. In some instances the skin of the throat is similarly 
affected. On the second day after the appearance of the inflammation 
reddish nodules are found and these gradually enlarge until they 
attain a diameter of one-half inch or more. The nodules are then 
gradually transformed into vesicles containing a fluid after which the 
usual pustule stage is reached with thicker more purulent contents. 
The usual treatment for the disease consists in careful handling and 
the application of disinfectant solutions to all ruptured vesicles upon 
tiie udder. 

Enteritis. — Under certain conditions the digestive tract of cattle 
may be so severely irritated, as to lead to an inflammation of the in- 
testines which is characterized by the production of a false membrane 
particularly in the large intestine. This form of the disease is known 
as croupous enteritis. The usual symptoms are depression, loss of 
appetite, and diarrhea with shreds of false membrane in the feces. 
The ordinary treatment consists in the administration of Glauber's 
salts in doses of 1 lb. followed by bicarbonate of soda in 2 oz. doses 4 



70 

times daily. Enteritis may also appear as the result of twisting or 
invagination of the intestines. In such cases there is evidence of 
severe colicky pains, the animal gets up and lies down frequently 
refuses food, and is sometimes bloated. There is little hope from 
treatment in this form of enteritis. Simple inflammation of the in- 
testines in cattle is comparatively rare. The course of the disease is 
from 4 to 6 days. A similar affection in the horse often proves fatal 
within a few hours. An ounce of laudanum may be administered in 
doses of 8 to 12 oz. of linseed oil every 4 to 8 hours. 

Hemorrhagic enteritis of calves is a septic disease of uncertain 
origin which may rapidly run to a fatal termination. In some cases, 
calves suddenly refuse food, show an elevation of temperature, and die 
within 12 hours. In this form of the disease hemorrhagic patches are 
almost always present under the serous membranes. The presence of 
hemorrhages serves as a ready means of diagnosing between this dis- 
ease and ordinary diarrhea of calves. 

Flukes. — Several species of liver flukes may occur in the bile ducts 
oi the liver of cattle, 2 of which, the common liver fluke and the large 
American fluke, are known to infest cows in this country. The com- 
mon fluke is much more frequently met with than any of the other 
species. Flukes are taken into the body with fodder and water. 
Cattle most frequently become infested with these parasites when 
grazing on marshy pastures. In young animals extensive infestation 
may produce fatal results. The symptoms resemble somewhat those 
produced by stomach worms. The beginning of the disease is not 
usually observed. At first there is a diminished appetite and an un- 
thrifty appearance of the skin. The mucous membranes become pale 
and the eyes somewhat dull. In advanced stages of infestation there 
are diminutions in the milk supply, unusual thirst, and edematous 
swellings on the lower portion of the body. In some instances, how- 
ever, the liver may be infested with the flukes to the extent of the 
destruction of a large portion of its substance without producing 
any disturbances in the condition or nutrition of the animal. The 
common fluke is a leaf-shaped worm with a conical head and flattened 
posterior portion. It occurs as a parasite more frequently in cattle 
than in sheep, goats, and hogs. It varies in length from 16 to 41 
mm. and in width from 6 to 12 mm. Sometimes the flukes penetrate 
into the circulation and. are carried to other parts of the body where 
they may be found in the form of tubercles particularly in the lungs. 
The embryonic stages of the liver fluke are passed in fresh water snails 
and from these animals the young flukes crawl upon the stems of 
grasses in marshy places and thus gain entrance to cattle or other 
animals which serve as the final host of the parasite. Medicinal 
treatment, is usually unsatisfactory. The disease may be prevented, 
however, to a great extent by drainage or avoidance of marshy places 



71 

or by introducing carp and frogs into infected waters. These animals 
feed upon the snails and thus destroy the flukes in their early stages. 

Flootncmd-mouth disease. — This highly infectious disease isj also 
known as apthous fever, epizootic aphthae, and by similar terms. It 
is of acute nature highly contagious and is characterized by the erup- 
tion of blisters in the mouth, on the feet, and between the toes. The 
disease is so readily spread by means of domesticated animals that in 
parts of Europe and elsewhere large cattle yards and abbatoirs are 
almost permanently infected. Cattle and hogs are most frequently 
affected but the disease also attacks sheep, goats, buffaloes, dogs, cats. 
and man. Man may become infected by coming in contact with the 
diseased animals or by drinking their milk. The intestinal affection 
produced from drinking the milk of diseased animals is of a serious 
nature. Ordinarily foot-and-mouth disease does not exist in the 
United States. A recent outbreak, however, called attention to the 
great economic importance of this disease in the United States and 
the dangers from its distribution. This outbreak was successfully 
combated and the disease was entirely eradicated by the stringent 
measures adopted by the Bureau of Animal Industry. While foot- 
and-mouth disease is known to be contagious and has been extensively 
studied for many years, its bacterial cause has never been discovered | 
The virus from the eruptions of the disease is exceedingly virulent as 
is also the milk from the affected animals. The period of incubation 
is from 3 to 6 days. The first symptoms of the disease are chills fol- 
lowed by high fever and the eruption of small vesicles upon the lips, 
tongue, gums, and other mucous surfaces of the mouth. A redness 
and inflammation of the feet particularly at the crown of the hoof 
and between the toes soon appear and vesicles are developed in such 
locations. After the disease is well established the appetite is ser- 
iously affected and an increased salivation is observed. A ropy saliva 
drips almost constantly from the mouth. The appearance of the 
disease in the feet is sometimes simultaneous in all 4 feet or may 
affect only 1 or 2. The udder. is frequently or in some outbreaks 
usually affected and becomes swollen and caked. In cases where the 
internal organs are affected before the vesicles appear upon the ex- 
ternal surface the disease may prove fatal within a short time. It 
should be a simple matter to diagnose this disease from the fact of 
its extremely rapid spread, high fever, and the general appearance of 
blisters upon the mouth and feet. It may be readily distinguished 
from cowpox by the fact that the eruptions or vesicles are soon rup- 
tured and never form true pustules. On account of the highly infec- 
tious nature of foot-and-mouth disease and the ability of the virus to 
maintain its virulence for long periods outside of the animal body it 
is necessary to* adopt strictest quarantine measures in all outbreaks of 
the disease and to slaughter and bury or burn all diseased and exposed 
susceptible animals. The rapidity with which the Bureau of Animal 



72 

Industry eradicated the outbreak in New England is proof of the 
efficiency of this method. 

Foot rot. — An inflammation of the foot between the claws may be 
brought about as a result of the operation of several causes. Foot 
rot may be due to overgrowth of the claws or inward pressure espe- 
cially where some foreign body becomes lodged between the claws. 
The disease may also be due to irritation from stable filth leading to 
a softening or ulceration of the skin between the claws of the foot. 
At times several cows in the same herd may become affected and in 
this way the fear of a contagion may arise. Such outbreaks, however, 
are due to the fact that the same causes operate upon a number of 
animals maintained under similar conditions. Simple outbreaks of 
foot rot of this sort may readily be distinguished from foot-and-mouth 
disease by the absence of fever, the absence of blisters in the mouth, 
and the failure of the disease to spread to hogs or other animals which 
are susceptible to foot-and-mouth disease. In cases of foot rot the 
animal goes lame, has a swelling of the hoof, and consequent separa- 
tion of the claws. An inflammation may cause the softening of the 
membrane between the claws and if neglected may lead to the forma- 
tion of abscesses with considerable suppuration. In the early stages 
of the disease before pus has buried beneath the horny covering of 
the foot a thorough cleansing of the affected parts and the application 
of a 1 per cent solution of carbolic acid or a similar antiseptic will 
check the disease. Creolin or corrosive sublimate may be used for 
this purpose. If the pus pocket has been formed underneath the horn 
of the hoof it is necessary to tear away the horn until the whole pocket 
is exposed after which the usual antiseptic treatment may be applied. 

Hematuria. — Various pathological conditions cause the presence of 
blood or the coloring matter of the blood in the urine and give rise to 
a condition known as hematuria or bloody urine. This is a compara- 
tively common affection in some localities especially among cattle 
which are allowed to graze on marshy undrained pastures. The con- 
dition is due, as a rule, to a structural disease of the kidneys or urinary 
passages. Albumen is present in the urine as well as the red coloring 
matter of the blood. Where hematuria is due to a severe strain of 
the loins by fractures, it is naturally associated with lameness or loss 
of control of the hind legs. In cases where bloody urine is due to the 
existence of specific diseases such as Texas fever and anthrax these 
diseases should be readily recognized. Hematuria may also be brought 
about by eating irritant plants such as hellebore, buttercup, oak leaves, 
and in some cases from excessive feeding on alfalfa or pea straw. 
The treatments for this trouble are naturally varied according to the 
cause. In general the administration of a purgative (1 lb. 
Glauber's salts) will remove the irritating substances from the in- 
testines and reduce the fever temperature. In cases where it is appar- 
ent that an excess of diuretic plants has been eaten it. may be desirable 



73 

to administer olive oil and laudanum. It may be useful also to apply 
hot fomentations or some warm protection over the loins. 

Hemorrhagic septicemia. — This name is applied to a highly infec- 
tious disease due to the action of Bacillus bovisepticus which affects 
cattle and various other species of domestic and wild animals. The 
organism which causes the disease belongs to the group which produces 
chicken cholera, swine plague, and septicemia of rabbits. The disease 
was first described in 1878 and in this country it has been observed in 
Minnesota, 'New York, Pennsylvania, South Dakota, Tennessee, 
Texas, Wisconsin, and the District of Columbia. In Minnesota the 
State Board of Health has made a detailed study of the disease and 
has investigated more than 90 outbreaks involving 3,000 animals. 
The mortality from hemorrhagic septicemia is very high exceeding 
on an average 95 per cent. The disease is a typical septicemia and 
the infection apparently takes place through small abrasions of the 
skin or injury to the mucous membranes from pieces of fodder and 
from other causes. The usual symptoms are loss of appetite, fever, 
stiffness, swellings of the legs and throat, a black-tarry excrement, 
and nervous excitement resembling meningitis. The meningeal 
.symptoms have been observed in a large number of cases. On this 
account certain investigators believe that some cases of hemorrhagic 
septicemia, have been mistaken for cerebro-spinal meningitis and corn- 
stalk disease, and have passed under these latter names. At present, 
the majority of students, who have worked with hemorrhagic septi- 
cemia, believe that cornstalk disease is merely one form of hemorrhagic 
. septicemia. The chief pathological lesions observed in eases of this 
disease are hemorrhagic areas of various size in the subcutaneous 
tissue, muscles, lymph glands, and throughout the internal organs. 
The spleen is rarely enlarged. According to Brimhall, whose investi- 
gations have been followed in this account, a distinct meningitis with 
an exudate almost filling the spinal canal is observed in all cases 
which showed meningeal symptoms. The differential diagnosis be- 
tween hemorrhagic septicemia, anthrax, blackleg, and cerebro-spinal 
meningitis due to a diplococcus is a difficult matter. A bacteriological 
investigation, however, should disclose the presence of Bacillus bovi- 
septicus in all cases of hemorrhagic septicemia and the presence of 
numerous hemorrhages in all parts of the body should assist in reach- 
ing a diagnosis. Thus far treatment, has proved to be entirely without 
avail. It is necessary, therefore, after outbreaks of this disease to 
remove and destroy all carcasses, isolate all exposed and sick animals, 
and apply thorough quarantine/ measures and disinfection to the 
premises. 

Horn fly. — In localities badly infested with horn flies, cattle are 
greatly irritated and kept in a state of worry by the attacks of these 
pests. The horn fly was originally introduced from Europe and has 
become quite generally distributed, over the country. The insect is 



74 

somewhat smaller than the house fly but closely resembles it in general 
appearance. It appears in swarms and has the habit of collecting in 
great numbers at the base of the horns from which fact its name appar- 
ently arises. The horn flies attack cattle especially upon the flanks 
and shoulders and places where they are not easily driven off by the 
tail or head. The pest, may be combated by applying a mixture of 2 
parts crude cotton-seed oil or fish oil and 1 part of pine tar to the 
flanks, back, and fore quarters. Fresh application should be made at 
intervals of about 10 days. The swarms of horn flies should also be 
removed by spraying cattle with kerosene emulsion or a mechanical 
mixture of crude petroleum and carbolic acid. One of the most suc- 
cessful methods of ridding cattle of horn flies consists in the use of a 
trap. A covered shed or passage way is provided for the animal to 
walk through; a well-lighted dome is constructed on one portion of 
the passage way the rest of which is kept as dark as possible. As the 
cattle pass along they crowd through a set of brushes which sweep off 
the flies. After being brushed away from the cows they arise into 
the lighted portion of the dome where they are captured. Cattle soon 
learn the purpose of this devise and thus rid themselves of horn flies. 
A systematic effort is being made to introduce parasites of the horn 
fly into Hawaii. 

Jaundice. — As soon as the condition of jaundice has been estab- 
lished there is a noticeable yellow tinge in the white of the eye and 
the mucous membranec of the mouth. The same appearance may be 
observed in parts of the skin which do not bear pigment. Jaundice 
must be considered as merely a symptom of some disease. An inflam- 
mation of the mucous membrane of the duodenum may mechanically 
obstruct the escape of bile and thus lead to a jaundice condition. In 
constipation there is a torpid condition of the intestines which leads 
to the absorption of the bile and a distribution of its yellow coloring 
matter through the body. Jaundice may also arise from excessive 
parasitism with flukes or tapeworms in the bile ducts, A congested 
condition of the liver due to continued high feed and lack of exercise 
may lead to jaundice. In all cases of this disease it is desirable to 
stimulate the action of the intestines and thus relieve the congestion of 
the liver and portal vein. For this purpose the diet should be of a 
laxative nature and purgatives should be administered such as a mix- 
ture of 16 oz. of sulphate of soda, and 1 pt. of molasses with 1 qt. of 
warm water. 

Joint ill. — Young calves within the first few months after birth are 
sometimes affected with a septicemic inflammation of the joints. 
When once established this inflammation persists and, is commonly 
associated with an infection of the navel. It is thus readily distin- 
guished from rheumatism which rarely occurs at so young an age and 
which has the tendency to shift from one joint to another. Joint ill 
is due to infection of the navel cord at the time of birth. The micro- 



75 

organisms thus introduced pass through the circulation and lymphatic 
system and finally become localized in the joints or elsewhere causing 
inflammations and abscesses. Affected joints are hot and sensitive. 
The animal is lame, shows a high fever and a purulent discharge from 
the navel. The liver and various other organs may also be affected. 
This trouble may be largely prevented by the adoption of proper sani- 
tary precautions. Cleanliness in stables and the use of disinfectants 
at frequent intervals will destroy the septic organisms which cause the 
disease. In case of joint ill the treatment should be chiefly antiseptic. 
In mild cases the affected joint may be painted with iodin or with an 
ointment of biniodid or mercury at the rate of 1 dram in 2 oz. of lard. 
If swellings are present containing purulent material this may be 
removed by the use of a hypodermic syringe and the cavity disinfected 
with suitable antiseptic solutions. 

Keratitis. — On account of the exposed position of the cornea this 
part of the eye is quite subject to injuries in the way of scratches, 
lacerations, etc. from sharp pointed stems of forage or from awns or 
other objects. In cases of diffuse keratitis the cornea becomes opaque 
from the extension of the process of exudation. Where the whole 
cornea is affected it shows a uniform grayish-white color. In favor- 
able cases the opacity disappears and the cornea becomes transparent 
again after a period of 10 days. In more severe cases, however, the 
vision is entirely lost and the cornea remains permanently opaque. 
In certain cases suppuration may take place as a sequel of diffuse 
keratitis. In treating this disease the animal should be placed in a 
dark stable and purgatives administered. If the health is not vigorous 
it may be desirable to give a tonic. The affected eye may be treated 
with a solution of nitrate of silver at the rate of 3 grains to 1 oz. of 
water. In order to clear up the cornea it may be well to apply twice 
daily a few drops of a solution containing 15 grains of iodid of potash 
and 20 drops of tincture of sanguinaria in 2 oz. of distilled water. 

Lice. — There are 3 species of sucking and biting lice which are 
parasitic on cattle. Perhaps the most common species is Haemato- 
pinus eurystemus, so-called short-nosed ox louse. The presence of this 
louse in large numbers causes a quite serious irritation of the skin of 
cattle and thus leads to loss of weight, and diminution in the milk yield. 
The adult female lice are about 1-8 to 1-5 of an inch long and half as 
broad as long while the males are somewhat smaller. The females 
deposit their eggs on the hair near the skin. This louse is one of the 
most difficult parasites to eradicate. Various remedies have been used 
as dips or washes or by the method of fumigation. Considerable 
benefit has been derived from the use of carbolic or tobacco sheep dips, 
kerosene emulsion, extract of larkspur-seeds, ashes, mercurial oint- 
ment and fumigation according to a method recommended by Osborn. 
.This method consists in confining cattle in a close box stall merely 
large enough to admit the cow and furnished with a close-fitting door. 



76 

A thick canvass sack is attached to the head of the animal so as to 
leave merely the eyes and nose exposed. After the apparatus has been 
arranged tobacco, pyrethrum or sulphur may be burned in the enclosed 
space for the purpose of destroying the lice. A closely related species 
(H. vituli) occurs on cattle but is somewhat less common. This 
species and the biting red louse (Tnchodectes scalaris) infest cattle 
to a considerable extent. All of these species may be treated in the 
same manner. Close attention should be given to cattle in order to 
prevent their becoming too extensively infested with these parasites 
since the animals may be so irritated as to rub off large patches of 
nair and lose greatly in condition. 

Malignant catarrhal fever. — This is a specific disease of cattle prob- 
ably due to the action of a micro-organism which thus far, however, 
has not been demonstrated. The disease appears not to be directly 
infectious but rather through intermediate carriers such as food and 
the filth of stalls and cow sheds. The disease usually appears in a 
sporadic manner and under certain conditions may attain the propor- 
tions of a local plague. The parts chiefly affected are the respiratory 
and digestive tracts, sinuses of the head and eyes. It is much more 
frequent in Europe than in this country but outbreaks have been 
reported in New Jersey, JSTew York, and Minnesota. Malignant 
catarrhal fever prevails most extensively in late winter and spring 
and affects chiefly young animals. The usual symptoms are chills 
followed by considerable elevation of temperature, trembling, abund- 
ant secretion of tears, swollen eye lids, sensitive eyes, and a general 
catarrhal condition of the respiratory and alimentary tracts. In mild 
cases recovery takes place within 3 or 4 weeks. The rate of mortality 
is very high, however, being as a rule from 50 to 90 per cent of all 
affected animals. In fatal cases death takes place within from 3 to 7 
days. In some cases ulcers may be found on the mucous membranes 
when post-mortem examinations are made and croupous deposits have 
been observed in the throat. There is no satisfactory treatment for 
this disease except the administration of palliative remedies such as 
antiseptic washes applied to the nose, eyes, and mouth; the adminis- 
tration of calomel in one-dram doses twice daily ; and the use of 
tonics containing ferrous sulphate, quinin, and subnitrate of bismuth 
Although malignant catarrhal fever is an acute disease of serious 
character and highly fatal consequences, it is usually found, post 
mortem, that the essential tissue of the internal organs is unaltered. 
According to Bollinger this furnishes an important means of 
diagnosing between malignant catarrhal fever and rinderpest. The 
meat- of animals affected with this disease has not been shown to cause 
harmful effects when eaten. It is uncertain whether the virus may 
be excreted with the milk but it appears highly probable that it might 
gain entrance to the milk as the result of the contamination of the 
floors of stables with the pathological discharges. 



77 

Malignant edema. — Various domestic and wild mammals as well 
as man may be affected by this disease which is of bacterial origin 
and of an acute nature. The bacterial cause of the disease is Bacillus 
.sepfocemiae gangrenosa. This organism is anaerobic and rarely found 
in the blood. Certain investigators including Arloing and Chauveau 
have claimed that cattle are immune to the disease. Kitt, however, 
has shown that the bacillus of malignant edema may cause extensive 
local swellings in cattle. As a rule, malignant edema is rarely met 
with in cattle but occurs chiefly as the result of infectious wounds of 
accidental occurrence or due to surgical operations. The pathogenic 
organism of malignant edema is of wide distribution and occurs in 
cultivated soil, polluted water, and the alimentary tract of herbivorous 
animals. The organism remains closely confined to the immediate 
region of inoculation but after death may penetrate into tissues quite 
remote from the point of entrance. The symptoms of malignant 
edema include muscular stiffness, trembling, a. rapid weak pulse, high 
temperature and a hot painful swelling at the point of infection. The 
swelling emits a crackling sound on pressure. The intestines are 
usually found in a normal condition and the lungs may be somewhat 
edematous. Malignant edema closely resembles blackleg but unlike 
the latter disease never appears as an extensive epizootic but always 
in isolated cases which may be explained as due to wounds received 
from various causes. A differential diagnosis between anthrax, black- 
leg, and malignant edema may be reached by inoculating guinea pigs, 
rabbits and chickens. All 3 species of these animals are destroyed 
by the organism of malignant edema while only guinea pigs and 
rabbits succumb to anthrax and guinea pigs alone to blackleg. Treat- 
ment should be mainly surgical and should consist in the incision of 
the local swellings and thorough treatment with antiseptics such aa 
5 per cent solution of carbolic acid or 30 per cent, solution of peroxide 
of hydrogen. 

Mammitis. — The mammary gland in cows is subject to a great vari- 
ety of inflammatory and other pathological conditions manv of which 
are groujjed together under the term mammitis or mastitis. Mammitis 
may be either of an acute or chronic nature. Acute catarrhal mam- 
mitis is also known as mammary catarrh and consists essentially of 
an inflammation of the milk ducts and canals. It is, therefore, anal- 
ogous to bronchitis in the lungs. As a rule the disease is not accom- 
panied by pronounced constitutional symptoms, the affected parts of 
the udder are hot, swollen, and painful to the touch and occasionally 
the swelling is so extensive as to partly conceal the teats. The milk 
is nearly always altered and consists of a pale yellow serum containing 
clots of casein and other material and is frequently tinged with blood. 
In the acute form of mammitis the disease appears suddenly and in 
milder cases may disappear within 6 or 8 days. If the disease runs 
a slower course it may be complicated with parenchymatous mammitis. 



78 

In the latter form of the disease the minute milk canals, acini, con- 
nective tissue and to some extent the whole gland is involved in the 
inflammatory process. This form of the disease is ordinarily com- 
plicated with other more dangerous symptoms. Parenchymatous 
mammitis may be due to various micro-organisms such as Staphylo- 
coccus mammitis, Galactococcus versicolor, G. fulvus, and G. albus. 
The general symptoms are loss of appetite, bloating, feeble pulse, and 
elevation of temperature. The local symptoms include an enormous 
enlargement of the mammary gland and an extension of the swelling 
forward along the abdomen. The milk in the affected quarters of the 
udder assumes a yellow color and even the unaffected quarters will be 
similarly altered within a few days. This form of the disease de- 
velops slowly and may, even in most favorable cases, cause an indura- 
tion complicated with the formation of abscesses or gangrenous pro- 
cesses. 

Chronic catarrhal mammitis is due to infection with Streptococcus 
and is of a, highly contagious character. It is also known by the 
terms streptococcus mammitis, contagious agalactia, and is synony 
mous with "gelber gait" or Switzerland. In cases of this disease a 
nodule appears at the base of the teat which gradually increases in size 
up to that of a man's fist and is surrounded by edematous tissue. At 
first the milk appears watery and blueish in color and contains leuco- 
cytes. Later it becomes viscid and is of a yellowish or pink color. 
This form of mammitis may be acute or chronic, but usually runs a 
slow course. In milch cows the disease is frequently complicated with 
inflammation of the joints. The affected parts of the udder become 
atrophied and transformed into fibrous tissue. On account of the 
great infectiousness of this disease and consequent rapidity with 
which it spreads through a herd it is necessary that affected animals 
be isolated promptly. Prognosis in this form of the disease is nearly 
always unfavorable. A certain percentage of cases die as a result of 
chronic abscesses and gangrenous process, while affected cows are 
scarcely ever useful for milk purposes after recovery. The mammary 
gland becomes almost or entirely sterile as the result of the disease. 

The various forms of inflammation of the mammary gland com- 
monly referred to by dairymen as garget are of frequent occurrence 
and since many cases do not persist, long and do not have any serious 
conclusions considerable indifference exists toward the treatment of 
the disease. In heavy milking cows the mammary gland is always 
enlarged just after calving and may show an elevation of temperature 
and an increased sensitiveness to touch ; the swelling may even extend 
forward along the abdomen. This congestion usually does not last 
for more than 2 or 3 days but may sometimes be greatly aggravated 
by exposure to cold or by neglect on the part of the milkers. In such 
cases the milk soon shows clots, pus cells, and a red tinge of blood. 

Treatment should consist in the copious administration of warm 



79 

drinks, the administration of heat to the body, and the use of camphor- 
ated ointment, weak iodin ointment or more drastic ointments to the 
ndder. Such application should be accompanied with thorough rub- 
bing. After the swelling and inflammation subside milking should 
be done with considerable care and. gentleness. In cases where fever 
has already occurred it is well to administer epsom salts in doses of 1 
to 2 lbs. and saltpeter in daily closes of 1 oz. In all cases of an in- 
fectious nature it is necessary to take great precautions to prevent the 
spread of infection. If the infected portion of the udder is milked 
before the other quarters, infection is almost certainly spread, to the 
latter if the hands are not previously washed and sterilized. The 
habit of milking diseased quarters of the udder upon the floor of the 
stable should be condemned since the streptococcus is present in such 
milk in large quantities and abundant opportunities are thus offered 
tor distributing the source of infection to other parts of the udder and 
to other cattle. 

Metritis. — An inflammation may involve merely the uterus or also 
the neighboring serous coat of the abdomen causing peritonitis. The 
symptoms of the disease ordinarily appear within 2 or 3 days after 
calving and consist of chills, coldness of the horns, ears, and legs, and 
an unthrifty appearance of the hair. The temperature is somewhat 
elevated, the pulse rate increased, and the appetite is lost. The chill 
is soon followed by fever during which the mucous membrane of the 
nose and mouth as well as the eyes appear red. The uterus is evi- 
dentlv more sensitive than under ordinarv conditions and discharges 
a fluid which is at first watery but later becomes yellow and finally 
reddish or brown, the latter color being due to hemoglobin of the 
blood. A certain percentage of these cases recover speedily some- 
times within 2 days, other cases develop into a chronic form while in 
more severe cases there is a septic infection terminating in ulceration 
or gangrene or general septicemia. The treatment for metritis should 
consist largely in the thorough washing of affected parts with anti- 
septic solutions. For this purpose permangenate of potash may be 
used at the rate of y 2 oz. to 1 qt. of water. It is ordinarily desirable 
to give Glauber salts in doses of iy 2 lbs. to which 1 oz. of ginger may 
be added. For reducing the sensitiveness of affected parts an ounce 
of laudanum may be given mixed with the same quantity of glycerin. 

Milk fever. — The term milk fever although generally used for this 
disease is somewhat of a misnomer since frequently there is no fever 
during the progress of the disease but on the other hand a subnormal 
temperature. Parturient paresis or parturient apoplexy are consid- 
ered as preferable to milk fever as names for this disease. Milk fever 
is confined almost entirely to high bred cows in good condition and of 
mature age. It has also been occasionally observed, however, in sows. 
As a rule the disease occurs only at or immediately following upon 
the time of calving. Several cases have been observed, however, which 



80 

occurred long after this period. The heavy milkers are most suscep- 
tible to milk fever and, as already indicated, the disease does not 
appear at the first and usually not at the second calving but more fre- 
quently at mature age. The nature and etiology of the disease have 
been investigated and discussed by numerous veterinarians but with- 
out definite results. The majority of investigators consider milk fever 
as an intoxication due to the formation of a poisonous metabolic prod- 
uct at the time of calving. The definite location of the toxin has not 
been established. Recently, however, Delmer succeeded in producing 
the disease by inoculating animals with small quantities of milk from 
affected cows. As predisposing causes to milk fever mention is usually 
made of close confinement in stalls, high temperature, electrical dis- 
turbances, constipation, or other digestive derangement, and a ple- 
thoric condition due to over feeding. The symptoms vary according to 
the form of the disease. In the so-called congestive form of milk fever 
there is sudden dullness, nervous movements of the hind legs, stag- 
gering weakness followed by complete inability to stand. The head 
and the ears become hot, the cow lies on her breast bone with the nose 
against the right flank. In the torpid form of milk fever there is no 
evidence of heat about the head and the attack appears more slowly. 
The cow soon lies down, however, and is unable to rise. There may 
be a subnormal temperature and complete or almost complete uncon- 
sciousness. 

Until recent years the treatment adopted for milk fever consisted 
largely in the use of purgatives, ice packs on the head, and the admin- 
istration of tincture of aconite until the fever disappeared. After 
this treatment, stimulants such as mix vomica, were given until the 
affected cow was able to stand. A large percentage of cases were lost 
by this treatment, however, and it was not until Schmidt devised his 
treatment which consists of injecting 10 gm. of iodid of potash into 
the udder that recovery was brought about in a large percentage of 
cases. Occasionally a second treatment with iodic! of potash was re- 
quired. Recently still better results have followed the distention of 
the udder with oxygen or ordinary filtered air. This treatment has 
the advantage of great simplicity, ease of application and quickness 
of results. In ordinary cases improvement is noted within a few min- 
utes and recovery usually takes place within from 2 to 6 hours. The 
udder should be tightly distended with air previously passed through 
absorbent cotton to remove all dust and bacteria. Good results have 
utes and recovery usually takes place within from 2 to 6 hours. The 
tion or with boiled water. The symptoms of paralysis observed in 
milk fever appear to indicate a condition of extreme anemia of the 
brain. The beneficial results which appear so promptly after the 
distention of the udder with such inert substances as air and boiled 
water indicate that the general blood pressure may perhaps be restored 
by the increased internal pressure of the udder due to artificial treat- 
ment. 



81 

Milk sickness. — In the heavily timbered lands and marshy areas of 
Georgia, Xorth Carolina, Tennessee, Pennsylvania, Ohio, Michigan, 
and other central States an apparently infectious disease has long pre- 
vailed under the name milk sickness. The nature of the disease is not 
understood but it is usually considered, as infectious on account of the 
fact that it is readily transmitted in the milk. Milk sickness may be 
readily transmitted, by means of the milk, to man and other animals 
with serious results. A curious fact noted in connection with this 
disease is that in milch cows during the period of full lactation no 
symptoms may be observed unless the animal is driven or violently 
exercised. After such treatment the animal trembles and shows in a 
mild form the usual symptoms of the disease. In bulls, steers, and 
dry cows the symptoms are much more serious. At first the affected 
animal appears lazy and stands apart from the herd with drooping 
ears. There is great thirst and constipation. As the disease pro- 
gresses muscular weakness becomes very pronounced until the animal 
is unable to stand, the legs and surface of the body appear cold and 
the animal is indifferent to his surroundings. The stupor gradually 
merges into complete coma with, death on the eighth to the tenth day. 
Similar symptoms are observed in man after drinking milk of affected 
cows. The rate of mortality is high. In cases which do not die 
recoverv takes place very slowly. ]STo specific treatment has been 
devised for this disease. Fortunately, however, milk sickness seems 
to disappear as soon as infected timber lands are partially cut out so 
as to allow free access of air, and infected marsh lands drained. The 
disease formerly prevailed much more extensively than at present, 

Mycosis. — There are a number of pathogenic fungi which affect 
cattle producing inflammatory conditions of the mucous membranes 
and other structures and commonly referred to under the name my- 
cosis. Recently Mohler has described a mycotic stomatitis of cattle 
which is of a sporadic and noninfectious nature and which attacks 
cattle of all ages on pasture especially milch cows. The mucous mem- 
brane of the mouth becomes inflamed and later ulceration appears, 
secondarily the feet may become swollen and frequently erosions are 
observed on the nose, udder, and teats. The disease is due to feeding 
on moldy or fungus-infected forage. Apparently several fungi may 
be concerned in the production of mycotic stomatitis. It is readily 
distinguished from foot-and-mouth disease (which it may resemble 
in some of its symptoms) by the fact that it is not infectious and, 
therefore, does not spread from affected cows to sheep or pigs which 
may be associated with them. The treatment of the disease should 
consist first in the removal of cattle from the pasture where the 
disease was acquired and feeding them upon soft foods until the 
mucous membrane of the mouth may be restored to a healthy condition 
by means of washes of borax, potassium chlorid, carbolic acid, creolin, 
lysol, or permangenate of potash. Quaranta observed cases of asper- 



82 

gillosis in the lungs of cattle. The disease was due to a pathogenic 
aspergillus and, produced tubercles which superficially resembled 
those of tuberculosis. In Pennsylvania Pearson and Kavenel studied 
a case of this disease due to Aspergillus fumigatus. The case occurred 
in a Jersey cow which had been failing for 6 month and finally died. 
An examination of the lungs showed that they were greatly distended 
and contained tubercles due to the action of the pathogenic fungus. 
The term mycosis may also be used to denote the pathogenic effects of 
smuts, molds, and rusts which produce more or less serious digestive 
disturbances without causing specific lesions in other parts of the body. 
The cause of disease produced by these fungi should be readily de- 
tected and after being detected it may be readily removed. 

Nagano,. — This is an infectious disease due to a protozoan blood 
parasite of the genus Trypanosoma. The majority of investigators 
including Laveran and Mesnil consider nagana as a specific disease 
affecting cattle and horses and distinct from surra, mal de caderas, 
and other related diseases. The conclusions of Musgrave and Clegg 
from work done in the Philippine Islands are directly opposed to this 
view. According to Musgrave and Clegg it is highly probable that 
surra, nagana, tsetse-fly disease, dourine, bovine surra, etc. are merely 
different names for one and the same disease which they prefer to 
call surra. Without entering into this controversy it may be stated 
that nagana is apparently transmitted from one animal to another by 
the bites of flies, fleas, or other insects with similar habits and thaf 
other methods of transmission may be disregarded as unimportant 
It appears to be impossible for the parasitic organism of nagana to 
pass through sound mucous membranes of cattle and pastures can 
not, therefore, become infected in the ordinary sense of the word but 
only in so far as they are infested with tsetse flies and other insects 
which may carry the organism of nagana. The chief symptoms of 
nagana are high fever, progressive anemia, weakness and swelling 
about the head,, legs, and abdomen. The disease runs a slow course 
lasting from 1 to 6 months in cattle and affects various other animals 
including mules, camels, dogs, etc. The spleen, lymphatic glands, and 
Uver become enlarged and diagnosis is rendered certain by finding 
the protozoan parasite in the blood. ISTo treatment thus far adopted 
has proved successful. 

Nephritis. — The kidneys may be affected with various forms of 
inflammation and may thus give rise to different symptoms of varying 
degrees of importance. The causes of nephritis are as varied as the 
forms of the disease. Irritant drugs, diuretic plants, exposure to 
severe climatic changes, blows, and other injuries may lead to some 
inflammatory condition of the kidneys. In cows which are not in a 
fat condition the kidneys are particularly exposed on account of the 
tact that they lie in close contact with the muscles of the loin. Severe 
exercise or worrying by dogs may also be the cause of a case of neph- 



83 

ritis. It has been observed that certain forage plants rich in nitrogenous 
substances such as vetches, pea straw, and, other leguminous plants 
may occasionally irritate the kidneys to such an extent as to cause in- 
flammation with symptoms of bloody urine. The symptoms of neph- 
ritis vary greatly. In some cases they are quite manifest while in 
others it is almost impossible to locate the affected part. In the cases 
which are due to blows the disease usually runs a regular course with- 
out serious complications. If evidence is obtained that nephritis is 
due to faulty fodder the diseased condition may obviously be corrected 
by a change of food. In all cases the first consideration is the removal 
of the cause. Attention must be given to the exclusion of acrid or 
diuretic plants from the diet. Sprained loins may be poulticed and 
the affected cow should be kept in a warm, dry building and covered 
with blankets if necessary. If fever is present it may be checked by 
the administration of tincture of aconite in doses of 15 drops every 4 
hours. 

Nodular disease of the intestines. — A disease of cattle characterized 
by progressive anemia and diarrhea during the later stages is caused 
by an intestinal worm known as Oesophagostoma inflatum. This 
parasite occurs in Europe and in various parts of the United States. 
Several outbreaks of the disease have been studied in Missouri by 
Drs. Connaway and Luckey. The disease is most prevalent among 
calves and yearlings. In cases of mild infestation the chief symptoms 
observed at first are slight loss of condition and extra feed require- 
ments. During the later stages of the disease emaciation progresses 
more or less rapidly and after 8 to 12 weeks may result in extreme 
anemia, diarrhea, and death. Diarrhea does not usually appear until 
within 5 to 15 days before the death of the animal. The symptoms 
of the disease are most pronounced when cattle are on dry feed. A 
partial recovery may take place if the animals are turned on good 
succulent pasture. The parasitic worm is found in considerable 
numbers in the intestines of infested cattle particularly in the colon 
and cecum and what appears to be the larval parasite of this species 
occurs in nodules in the walls of the intestines. Preventive treatment 
is the most important consideration in the control of this disease. 
Animals from infested areas should not be introduced into a herd 
without a preliminary period of isolation or quarantine. The para- 
site may infest in a permanent manner certain marshy pastures and 
from such sources healthy cattle may readily become infested. Drain- 
age and cultivation of such areas is an efficient preventive remedy. 
No medicinal remedies have proved effective in the control of this 
disease. , ' 

Osteomalacia. — In certain regions a brittleness or softening of the 
bones in cattle is observed giving rise to a disease known as osteoma- 
lacia or creeps. The latter name refers to the uncertain gait which 
characterizes affected animals. The disease appears for the most part 



84. 

in adult animals and is due to a decalcification of the bones which 
renders them more spongy. The periosteal covering of the bones is 
easily stripped off. Milch cows seem to be particularly susceptible 
to the disease probably on account of the fact that unusual demands 
are made wpon their nutritive powers during pregnancy and lactation. 
A pronounced emaciation gradually appears with the symptoms of 
depraved appetite and intestinal catarrh. J. W. Parker investigated 
this disease in certain regions of Texas where it appeared to occur as 
the result of improper nutrition. In advanced cases the skin was dry 
and tense and animals' ribs had been broken by pressure in lying down 
or other strains. Some of the affected cattle were parasitized by 
stomach worms but these parasites could not be considered as the sole 
cause of the disease. According to Parker creeps must be considered 
as due to a lack of essential elements particularly lime in the soil. 
The treatment to be recommended consists in a change of food and 
the addition of lime salts to the ration. Abundant grain feed should 
be given including beans, cowpeas, cotton-seed meal, or wheat bran. 
It may be desirable also to use phosphorus in 1 grain doses twice daily. 
Some benefit is to be derived from the change of pasture and the ad- 
ministration of common salt and bone meal. 

Pericarditis. — An inflammation of the pericardium or heart sac is 
sometimes associated with rheumatism, pneumonia, pleurisy, and in- 
juries. It apparently occurs also as an independent disease following 
severe exposure to inclement weather. The symptoms include chills, 
fever, dullness, hard pulse, quickened breathing, and muscular spasms, 
the heart beat is usually loud and its peculiar character may be noted 
by placing the ear against the chest. After fluid has collected in the 
pericardium the sound of the heart beat is partially lost and is replaced 
by a churning sound. When pericarditis occurs in association with 
rheumatism or other diseases the treatment should be such as will 
counteract these diseases. It is particularly to be recommended that 
the animal be kept in a warm place and bandaged so as to furnish 
protection against the loss of animal heat. In cases of pericarditis 
which result from penetrating wounds from the first stomach little 
help can be furnished by medicinal treatment. Such cases may arise 
as the result of the puncture of the pericardium by sharp bodies which 
have been swallowed with the food. In mild cases not due to puncture 
and not complicated with serious pleurisy, it is desirable to give a 
purgative and laudanum in 2 oz. closes provided there is evidence of 
great pain. Otherwise the laudanum should not be given on account 
of its constipating effect. 

Peritonitis. — Cattle are less susceptible to peritonitis than horses. 
The usual cause of the disease is to be looked for in wounds of the 
abnominal wall, intestines, stomach, or uterus. Peritonitis may result 
as an extension of metritis or enteritis. It also frequently follows 
upon castration where no antiseptic precautions are taken. The 



85 

symptoms are chills, uneasiness, undue sensitiveness of the abdomen, 
dry muzzle, loss of appetite, hard pulse, and constipation. In animals 
dead of the disease the lining membrane of the abdomen and intes- 
tines is reddened and a reddish watery fluid is observed in the abdom- 
inal cavity. Peritonitis which arises as a result of wounds should 
be treated: by applying antiseptics to the wounds and by the adminis- 
tration of opium in doses of 2 to 3 grams followed by rectal injections 
to prevent too great constijDation. Borax in 6 oz. doses has been 
recommended by Harms. The diet should be of a laxative nature 
and the body should be kept warm by blankets. 

Pleuro-pneumonia. — This disease is generally distributed through- 
out Europe and other parts of the world but has not been observed in 
the United States since 1892 when the last outbreak was eradicated by 
the Bureau of Animal Industry. The bacterial cause of pleuro- 
pneumonia is not known. Infection may be carried either by diseased 
cattle or by attendants, feed, dogs, and by other means. The disease 
is essentially due to inflammation of the lungs and pleura and affects 
cattle only. JSTo good evidence has been presented to show that the 
disease may be transmitted to man either by eating the meat or drink- 
ing the milk of affected animals. The period of incubation in pleuro- 
pneumonia ranges from 3 to 6 weeks. The symptoms vary consid- 
erably in different cases. In acute cases they appear suddenly with 
rapid and difficult breathing accompanied with moans and other 
evidence of pain. The back is arched, the head extended, and the 
temperature ranges from 104 to 107 °F. In very mild cases there 
may be a cough for a week or more before an elevation of temperature 
occurs. In such cases recovery may take place. The rate of mortal- 
ity varies from 10 to 50 per cent and in general from 80 to 90 per 
cent of the herd becomes affected. The prevention of the disease 
must depend largely on the effective maintenance of quarantine and 
the destruction of diseased animals. If an outbreak should occur in 
a herd it is highly important that all affected animals be immediately 
slaughtered and destroyed in a sanitary manner after which the 
stables and exposed parts of the premises should be thoroughly 
cleaned and disinfected. Medical treatment is of no avail. 

Poisons. — Cattle like other domesticated animals are subject to 
mineral and plant poisons of various sorts. In this connection brief 
notes may be given on some of the more common sources of poisoning. 
Some cases of mineral and plant poisoning arise from the injudicious 
administration of drugs while, others are of accidental origin or arise 
from grazing on poisonous plants in the field. 

On account of the extensive use of Paris green and other arsenical 
preparations for destroying insects and for dipping animals oppor- 
tunity is frequently offered to cattle to become poisoned with these 
substances. In some cases also arsenic is used excessively for a tonic 
or in so-called condition powders. The symptoms of acute poisoning 



86 

from arsenic are those of colic, restlessness, and frequent getting up 
and lying down, the abdomen is senstitive, and violent diarrhea fol- 
lows in a few hours. In chronic poisoning with arsenic the symptoms 
resemble those of chronic intestinal catarrh. The best antidote for 
arsenic is a solution of hydrated oxid of iron which may be made by 
mixing a solution of sulphate of iron with 1 oz. of magnesia in one- 
half oz. of water. This dose may be repeated if necessary. The solu- 
tion should contain 4 oz. of sulphate of iron. 

Lead poisoning may occur as the result of licking freshly painted 
surfaces or from the administration of excessive doses of sugar of 
Jead. The symptoms are dullness, colic, loss of muscular control, 
convulsions, bellowing, and delirium. Quite recently cases of lead 
poisoning occurred in Utah as the result of feeding sugar-beet pulp 
w r hich had lain in contact with pieces of lead ore in freight cars. 
Treatment should consist in the administration of purgatives, bromid 
of potash, and dilute sulphuric acid in y 2 oz. doses. Occasionally 
cases of poisoning are noted as the result of eating copper salts, zinc, 
phosphorus, mercury, mineral and vegetable acids, alkalis, kerosene, 
carbolic acid, saltpeter, and overdoses of vegetable alkaloids. These 
cases, however, are of such rare occurrence that they need not be 
described in this connection. The drug which is perhaps most com- 
monly given in cases of fever is aconite. This produces a paralysis 
of the motor and sensory centers of the brain and spinal cord, de- 
presses the action of the heart, and in overdoses causes death by 
paralysis of respiration. 

Among the various plant poisons which may be taken by cattle 
while grazing in the field a few of the more important may be 
mentioned. Loco weeds occur throughout the States and Territories 
west of the Mississippi River and especially in the southern portion 
of this large area. They cause numerous cases of poisoning among 
cattle but such cases are not so frequent as in sheep and horses. The 
symptoms are indicated by the name of the plant which means crazy 
weed. Affected animals usually separate from the herd and indicate 
in various ways a loss of muscular control and defectiveness of the 
special senses, they become frightened at common or imaginary ob- 
jects and sometimes develop vicious and dangerous tendencies. The 
proper treatment consists in the removal of cattle from areas in which 
loco weeds grow and feeding with nutritious cultivated fodder plants. 
In various parts of the Rocky Mountain and Pacific Coast States, 
pastures are infested with aconite and larksupr. In certain parts of 
the Wasatch Mountains of Utah a large number of cattle are annually 
lost as the result of eating common aconite (Aconitum columbianum) 
which grows abundantly in clusters of bushes which line the small 
streams and in bunches of coarse grass, etc. This species of aconite 
paralyzes the vagus nerve and thus increases the force and rate of 
the pulse. The sensibility of the animal is not much affected but 



87 

death is ultimately caused by paralysis of respiration. Various species 
of larkspur especially Delphinium hicolor and D. glaucum cause 
losses among cattle in mountain pactures. These plants cause symp- 
toms similar to those produced by over doses of aconite, the gait 
becomes stiff and irregular, the muscular control is lost, and the animal 
tinally falls to the ground in convulsions. Water hemlock (Cicuta 
maculata and C. occidentalis) causes the death of cattle with violent 
symptoms if the base of the stems and roots are eaten. The symptoms 
are the manifestations of severe pain, running away from the herd, 
cerebral frenzy, weak pulse, rapid breathing, and violent muscular 
spasms. A large number of other plants such as death camas, lupines, 
etc. occasionally poison cattle but a discussion of these plants would 
occupy too much space for present purposes. In case of poisoning 
the best remedy which can be suggested is the administration of per- 
manganate of potash dissolved in water in doses of 30 to 50 grains. 
This drug if administered immediately after the symptoms appear 
oxidizes and renders inert those portions of the poisonous plant which 
still remain in the stomach. The other symptoms must always be 
combatted by proper remedies such as chloral hydrate, morphine, or 
Indian hemp for violent convulsions, aconite for a too rapid and hard 
pulse, strychnin or atropin for a weakened and irregular pulse. 

Among the fungi which may poison cattle we may mention a few 
common examples. The poisonous effects of ergot appear chiefly in 
the spring of the year. This fungus develops in the heads of certain 
grasses such as wild rye grass, prairie June grass, several species of 
couch grass, blue joint, etc. Cattle seem to be slightly more suscept- 
ible than other animals to the effects of ergot. It has the effect of 
contracting the muscles of the small blood vessels and stopping the 
circulation particularly about the ankles. The tissue below the af- 
fected point does not receive the blood supply and consequently dies 
and sloughs off as a result of gangrene. There is no satisfactory 
medical treatment. Chloral hydrate has the effect of dilating the 
blood vessels and the main reliance must be placed on the removal of 
the cause, viz., the ergotized feed. 

In a few instances smutty oats have been fed with serious results. 
In one case one-half of a large herd of dairy cows died with symptoms 
of gastritis and with cerebral excitement within 24 hours after feeding 
on oat hay which was excessively smutty. The conditions under which 
smutty, rusty, or moldy forage produces diseases are not thoroughly 
understood. 

Rabies. — This disease affects dogs most frequently but all of the 
domestic animals and man are susceptible. As is generally well 
known rabies or hydrophobia is transmitted through the agency of 
bites of affected animals, usually dogs. The frequency of cases in 
cattle naturally varies from year to year and according to the freedom 
of access which rabid dogs may have to the cattle. Occasionally it 



may happen that a rabid dog bites several cattle belonging to the 
same herd and in such instances the disease appears after the usual 
period of incubation which varies somewhat in different individuals. 
In cattle the disease usually assumes the more violent type but in 
some outbreaks dumb rabies or the paralytic form prevails, the animals 
become restless and irritable, the eyes are inflamed, prominent, and 
with dilated pupils. Animals bellow as if in pain, twitch the tail, 
and sometimes attempt to bite. In the dumb form of rabies in cattle 
there is evidence of paralysis with symptoms of nervous exhaustion, 
dullness, and lameness in the legs. In certain parts of Kansas and 
other western States several outbreaks of rabies have recently occurred 
on a quite extensive scale. The cause was apparently to be sought 
in homeless dogs which were allowed to wander about at will. Rabies 
may be readily distinguished from tetanus by the fact that in the 
latter disease the animals are affected by long continued muscular 
spasms and do not show any signs of viciousness. Treatment for this 
disease is useless after the symptoms appear. If the biting of cattle 
by dogs is observed the wounds should be immediately cauterized with 
a hot iron, with zinc chlorid in a 10 per cent solution or strong nitric 
acid, otherwise affected animals must be ultimately destroyed. The 
Pasteur method of treatment which has proved so valuable in prevent- 
ing the disease in man would probably be effective in treating cases 
of cattle but would be a very tedious and expensive method. 

Retention of the afterbirth.— This trouble affects various domesti- 
cated animals but is most frequently observed in cows. The cause of 
this is to be sought in the firm connections between the fetal mem- 
branes and the uterine walls. The symptoms of the trouble may be 
readily observed since the membranes are ordinarily visible and emit 
a disagreeable odor. If no attention is given to the cow septic troubles 
may appear and lead to serious disease or death. Treatment should 
consist in the careful removal of the afterbirth, the administration of 
laxatives such as Glauber salts in iy 2 lb. doses and ergot in doses of 
1 oz. to produce uterine contractions. Thorough antiseptic treatment 
should then be applied with 1 per cent solutions of carbolic acid or 
solutions -of permanganate of potash, corrosive sublimate or other 
disinfectants. 

Rheumatis?n. — This is a constitutional disease apparently due to 
an abnormal condition of nutrition and is characterized by lameness, 
stiffness of the joints, swellings, and fever. The joints are the parts 
most frequently affected and the disease may assume an acute or a 
chronic form. The causes usually assigned for the origin of rheuma- 
tism are exposure to cold or dampness especially when the animal is 
overheated or after severe exercise. Rheumatism sometimes appears 
without apparent cause or it may follow as one of the consequences of 
some other disease such as pleurisy. In the chronic form of rheuma- 
tism of the joints there is a tendency for the swelling to shift about 



89 

from one joint to another. In acute articular rheumatism the symp- 
toms appear suddenly, thirst is usually increased, respiration and 
pulse are exhilarated, and the temperature rises sometimes to 108°F. 
In the prevention of rheumatism attention should be given to the 
physical comfort of the animals and the protection against cold and 
moisture particularly in buildings. The ration should be compounded 
so as to furnish variety and, abundance of nutritive elements. In 
chronic rheumatism local treatment may be administered together 
with tonics. The local treatment may consist in hot or cold packs, 
friction and liniments, or blisters according to the severity of the 
case. A system of constitutional treatment is sometimes adopted in- 
volving the use of sodium salicylate in doses of ^ oz. every 2 hours 
and repeated 4 or 5 times until relief is obtained. 

Rinderpest. — This disease is known under various names such as 
cattle plague, rinderpest, contagious typhus, steppe murrain, etc. 
This has been known for centuries in Europe and Asia but does not 
occur at present within the limits of the United States proper. It 
has caused serious ravages, however, in the Philippines. The disease 
is of a highly infectious nature but its bacterial cause is not known. 
The virus may be transmitted from healthy to diseased animals in 
the excreta and discharges from the body or may be carried on the 
slices or clothing of attendants. The digestive organs are chiefly 
affected. The period of incubation varies from 3 to 9 days. The 
first symptoms are high fever, chills, and rapid pulse. The animal 
shows great debility, drooping of the head and ears, and dry muzzle, 
the back is arched, and the forelegs are drawn under the body. As 
the disease progresses the mucous membranes of the digestive and 
respiratory organs become greatly inflamed. Upon post-mortem ex- 
amination reddened spots with diseased and dead tissue or ulcers are 
observed in the various parts of the alimentary tract and similar 
changes may be found in the mucous membrane of the respiratory 
organs. No successful treatment for the disease has been devised. If 
an outbreak should occur it is desirable that the strictest quarantine 
measures be immediately put in operation and all affected animals 
should be slaughtered and rendered innocuous. Susceptible animals 
may be inoculated with pure bile from an animal just dead of the 
disease or by glycerated bile followed by inoculation with virulent 
blood or pure bile or finally by simultaneous inoculation of virulent 
blood and serum. An active immunity is thus brought about in inoc- 
ulated animals which persists until all danger from the outbreak is 
passed. In fact in experiments in South Africa is appears that such 
immunity persists for about 4 years. 

Ring-worm. — Various parasitic fungi may attack the skin of cattle. 
Ringworm is a skin disease due to a fungus of this sort usually known 
by the name Trichophyton tonsurans. The fungus attacks the outer 
layer of the skin and the hair and may be readily transmitted from one 



90 

animal to another. The disease is therefore highly infectious. Af- 
fected cattle may be recognized by the circular bare patches on the 
skin. These patches become inflamed and later show a slight exudation 
followed by the formation of pus. The bare patches are due to the 
fact that the fungus causes the hair to break off at the surface of the 
skin. One form of ringworm which affects cattle and may be trans- 
mitted from cattle to other animals or even man is due to another 
fungus Achorion schonleinii. The crusts over the patches in this 
form of the disease are pale or sulphur color later becoming darker. 
This form of the disease may be recognized by the peculiar mousey 
odor of the patches. In treating ringworm the crusts should be re- 
moved by means of a brush and soap suds after which acetic acid may 
be applied or tincture of iodin, sulphur ointment, or similar anti- 
septic substances. 

Scabies. — Mange or scabies in cattle is a parasitic disease due to 
the presence of a mite in the skin. The disease has long been known 
among cattle of the southwest and affects cattle quite generally through- 
out the Rocky Mountain region. It is especially prevalent among 
range cattle since the best opportunity for infection is found among 
cattle managed in this way. Scabies appears most prominently in 
winter or spring especially when cattle are in poor condition or on 
dry feed.. After affected animals have been for sometime on cut 
grass and have improved in condition the infection with the mange 
mite may not be apparent. It has often erroneously been assumed 
on this account that scabies does not affect fat cattle and that spon- 
taneous recovery may take place. This assumption has had the un- 
fortunate result of spreading infection more widely than would have 
been the case if it had been recognized that such animals are still 
mangy. The first symptoms are evidence of itching and rubbing espe- 
cially in the region of the neck and shoulders. The mange spreads 
gradually along the back and sides but does not ordinarily occur on 
the inside of the legs or on the less-thickly covered portions of the 
abdomen. The coat looks rough and does not shed off so readily or 
smoothly in the spring. After the hair comes off from badly affected 
patches the bald area apparently gets well and the hair grows again. 
After one mangy animal is introduced into the herd the disease spreads 
quite rapidly especially if they are maintained in close quarters. 
Scabies may be best treated by dipping. Hand dressing has given 
excellent results in Montana and elsewhere but as a rule dipping in 
cages or vats is to be recommended. In the choice of a dip it is best 
to fix upon a mixture of lime and sulphur. There are several objec- 
tions to the proprietary coaltar dips such as a disagreeable odor, varia- 
tions in composition, poisonous and irritant effects, and expensiveness. 
Ordinarily such dips cost 2 or 3 times as much as the lime and sulphur 
dip. Mayo on the basis of extensive experience with scabies in Kansas 
recommends that a dip be made so as to contain 12 lbs. of lime and 



91 

20 lbs. of sulphur for each 100 gal. of the mixture. This mixture 
should be boiled for 2 hours in about 25 gal. of water after which it 
is diluted. The sediment may be mixed with the dip since the whole 
mixture appears to be more effective when the sediment is included, 
and is not injurious to cattle. Cattle affected with scabies or exposed 
to the disease should be dipped in the fall or in the spring. The dip 
should be maintained at a temperature of 110 °F. and the dipping 
should be repeated 10 days after the first operation. 

Scouring. — Indigestion involving some form of scouring is a fre- 
quent trouble in calves. The disease commonly referred to by this 
name may be of a simple or contagious nature. Scouring in skim 
milk calves may be due to feeding sour fermented milk which has 
developed injurious properties as the result of uncleanly handling. In 
sucking calves the disease may be due to abnormal composition of the 
cows' milk as the result of eating improper rations or irritant drastic 
plants. Under abnormal conditions in the cow the milk may become 
greatly changed in composition and may exercise a strongly laxative 
effect. In slight cases of scouring it is sufficient to give attention to 
the cause of the disease, prevent undue fermentation in the milk, or 
improve the rations of the cows. Rye bran may be added to the milk 
of scouring calves and exercise a good effect upon the alimentary tract. 
Good results are had from adding formalin to the milk at the rate of 
1 :1000. The most acute and deadly form of diarrhea in the new-born 
calf is commonly called contagious scouring or white scours and 
results in death within 24 to 36 hours. The symptoms are weakness, 
prostration, rapid breathing, subnormal temperature, and offensive 
discharges. This form of the disease usually appears during the first 
2 or 3 days of life. It is due to infection with a bacterial organism 
belonging to the group of hemorrhagic septicemia. The organism 
gains entrance to calves through the unhealed navel cord at the time 
of birth or soon afterward. No successful treatment is known for 
white scours. In preventing the disease attention should be given 
cleanliness of stables, disinfection of the navel of calves after birth, 
aud the disinfectant treatment of cows. 

Screw-worm fly. — The screw-worm fly may be distinguished by ita 
bine body, red anterior portion of the head, and 3 black lines on the 
thorax. It is generally distributed throughout tropical and temperate 
America. The adults deposit their eggs in refuse matter, flesh wounds, 
carcases of animals, and other similar material. The eggs hatch 
within a few hours and the larvae grow to maturity very rapidly. The 
larva of this pest is one of the most important insects which affect 
cattle and other domestic animals. In some parts of the southern 
States it is absolutely necessary that wounds of cattle be attended to 
in order to prevent their infestation by this pest. In some cases it 
appears that the screw-worm fly may deposit eggs upon the skin of 
cattle where the ticks have been crushed. In order to prevent the 



92 

adults of the pest from depositing their eggs in wounds the latter 
should be treated with dilute solutions of carbolic acid and subse- 
quently coated with pine tar or some other substance which repels the 
insects. 

Staggers. — The term staggers has been applied to various forms of 
meningitis and encephalitis and has also been used as synonymous 
with frenzy, coma and other similar conditions observed in cattle. 
Tn some localities mad staggers, sleepy staggers, and grass staggers 
have been used as common terms for what is apparently the same dis- 
ease. Staggers may be due to severe blows on the head, brain tumors, 
ergot or other deleterious matters in the food, excessive infestation with 
parasites, ingestion of mineral and narcotic poisons, severe exertion, 
or excitement. The first symptoms of importance are those of frenzy, 
but usually the animal is sleepy and shows but little inclination to 
move, trembling and muscular spasms followed by delirium and 
bellowing or staggering. Recoveries from this disease are quite rare 
even when the best attention is given. When the pulse is hard it may 
be well to bleed the animal. Epsom salts may be administered in 
iy> lb. doses and attention should be given to the animal during con- 
vulsions to prevent it from suffering injuries. 

Stomach worms. — Calves as well as sheep and goats are frequently 
infested with a stomach worm known as Strongylus contortus. The 
symptoms of infestations are not characteristic and are not always the 
same. Ihere are usually digestive disturbances accompanied at first 
by constipation and later by diarrhea ; the appetite becomes irregular 
and depraved. Infestation with the parasite may come about through 
contaminated feed and water. Apparently marshy pastures may be 
important sources of infestation. The treatment recommended by 
Stiles consists in the administration of 1 per cent of coal tar creosote 
in doses of 5 to 10 oz. for calves, 1 pt. for yearlings, and 1 qt. for 
adult cattle. Almost equally satisfactory results may be obtained from 
the use of gasolene in doses of y% oz. for calves, 1 oz. for yearlings, 
and ly? oz. for adult cattle. In general it is desirable that the gaso- 
lene treatment be given only after a period of fasting from 12 to 18 
hours and that no water be given for at least 2 hours after the gasolene 
has been administered. Wheeler obtained excellent results from the 
use of a 1 per cent solution of lysol and other coal tar products in 
doses of 6 oz. These remedies may be administered in the form of a 
drench. For this purpose the animal may be left standing on all 4 
feet or may be thrown according to the docility of the animal. In 
preventing stomach worms attention should be given to the pastures. 
Marshy pastures should be drained and water should be supplied to 
cattle in troughs rather than allowing them to secure it from pools 
which may become infected. 

Stomatitis. — ISTecrotic stomatitis also known as calf diphtheria is 
a highly contagious inflammatory condition of the mouth occurring 



93 

chiefly in young cattle and characterized by the presence of ulcers or 
necrotic patches and by constitutional symptoms due to the toxins 
caused by the pathogenic organism. Recently many cases of the dis- 
ease have been reported in Colorado, South Dakota, and Texas and 
have commonly been referred to as sore mouth. The disease is due 
to infection with Bacillus necrophorus, is highly pathogenic for cattle, 
horses, hogs, sheep, rabbits, and various other animals. The chief 
lesions in necrotic stomatitis are observed in the mucous membrane 
of the mouth and pharynx. They may extend, however, to the nasal 
cavities, larynx, trachea, and lungs. Infection apparently takes place 
through an abrasion in the mucous membrane. Symptoms may be 
local or constitutional the latter being due to toxin. The period of 
incubation varies from 3 to 5 days and the first symptoms are dripping 
of saliva from the mouth followed by a formation of a sharply out- 
lined necrotic patches of the mucous membrane of the mouth. With 
the appearance of g;eneral symptoms the temperature may arise to 104 
to 107°F. The disease spreads with great rapidity in affected herds 
and in acute cases runs its course in from 5 to 8 days followed by 
death in a large percentage of affected animals. Spontaneous recov- 
eries are rare. For preventing the disease chief reliance must ha 
placed on the separation of sick animals, disinfection of the mouth 
and nasal passages of all diseased animals, and disinfectant measures 
applied to stalls and buildings. Treatment of diseased animals con- 
sists almost entirely in the careful and thorough cleansing and disin- 
fection of all diseased parts of the mouth and nasal passages. For 
this purpose a 1 per cent solution of carbolic acid may be used or 
Lugol's solution containing 1 part of iodin, 5 parts potassium iodid, 
and 200 parts water. 

Teat Disease. — The teats of cows may become injured as a result of 
chilling in winter, from contact with stagnant, filthy water, or from 
lying in unclean stables. Similar injuries may be produced by the 
calf. These injuries may be of a very slight nature or may result in 
chapping, with the formation of cracks or sores, and in some instances 
in inflammation of the udder to such an extent as to resemble a serious 
case of mammitis. This form of trouble is best treated by applications 
of vaseline or a combination of spermaceti and oil of sweet almonds 
in equal parts. Where the affected parts are greatly irritated, it may 
be well to use a wash containing one dram of sugar of lead in one pint 
of water. 

The milk duct may become closed as a result of concretion of 
casein, the formation of calcareous deposits from the milk, the devel- 
opment of warty or other growths inside of the duct, the thickening 
of the inner mucous membrane, or the transverse growth of a thin 
membrane. These troubles usually arise during the later stages of 
lactation or while the cow is dry. An obstruction in the milk duct 
may best be removed by the use of the spring dilator or some form 



94 

of milk tube, with which all dairymen are provided. Care should be 
exercised in introducing any instrument into the milk duct, since 
infection may easily be carried on unclean instruments and may 
result, in the development of mammitis. 

Texas fever. — This disease is also known as Spanish fever, Southern 
cattle fever, redwater, and by various other names. It is an infectious 
disease of cattle due to the presence of a protozoan blood parasfite 
known as Pyrosoma bigeminum. In the United States the distribu- 
tion of Texas fever corresponds generally with that of the cattle tick, 
with certain exceptions where the cattle tick appears to be non virulent 
The characteristic symptoms of the disease are rise of temperature, 
destruction of the red blood corpuscles and consequent hemoglob- 
inuria or redwater which is due to the liberation of the blood coloring 
matter from the disintegrated blood corpuscles. The blood parasite 
is carried from one animal to another by the cattle tick, in which the 
parasite may live for long periods. Ticks which are attached or have 
been attached to cattle which are affected with Texas fever, or which 
have recovered from the disease, may contain the blood parasite and 
may, therefore, transmit the disease to healthy cattle from which they 
suck blood. The parasite is introduced into susceptible cattle through 
the puncture which the tick makes in obtaining blood. The period of 
incubation for this disease varies from 2 to 5 weeks, but the symptoms 
usually appear within 9 to 14 days. The rate of mortality is very 
high under ordinary conditions and medical treatment is of little 
avail. Recently certain experiments reported from Germany indicate 
that hemoglobin, or the red coloring matter of blood, may be useful 
in the treatment of Texas fever. The value of this treatment depends 
upon the obvious fact that in Texas fever the affected animals are 
very anemic on account of the destruction of the blood corpuscles. 
The use of hemoglobin, therefore, restores some of the lost coloring 
matter. 

The quarantine line for Texas fever has been extended across the 
country by the Bureau of Animal Industry from Virginia to Mexico 
in a somewhat irregular course so that the Southern States, including 
a portion of southern California, lie within the Texas fever zone. 

When cattle are infested with ticks during early life, they suffer 
from a mild form of the disease and in a large percentage of cases 
recover. After recovery they are immune to further attacks of the 
disease. This fact has been utilized in the production of artificial 
immunity to Texas fever. It has been found possible to inoculate 
young cattle with from 1 to 2 cubic centimeters of the defibrinated 
blood of animals which have recovered from the disease. A mild 
form of Texas fever is produced by this inoculation within 8 or 9 
davs and usually persists for 7 or 8 days. A secondary fever period 
may occur after about 30 days and may persist for one week. Tt is 
less serious', however. Young animals withstand inoculation better 



95 

than older ones and a larger percentage become immune. Different 
investigators have recommended different plans of immunization. 
According to recent experiments, however, it appears best to ship 
northern cattle south into the Texas fever area and keep them on 
pastures which are free from ticks until after the period of inocula- 
tion fever has passed. The advantage in this method consists in the 
fact that cattle do not have to be transported by railroad immediately 
after recovery from inoculation. The successful development of this 
system of vaccination has resulted in a great improvement of the 
dairy herds of southern States, since it is now possible to immunize 
pure-bred cattle for use in the Texas fever area without danger of 
their acquiring the disease. At present a systematic attempt is being 
made to eradicate the ticks. 

Tuberculosis. — Of all the diseases which affect cattle, tuberculosis 
is the most important, not only on account of its destructiveness to 
cattle but also on account of the great prevalence of the disease among 
human beings. Tuberculosis is an infectious disease characterized 
chiefly by the development, in various organs and tissues of the body, 
of tubercles of varying size due to the action of the tubercle bacillus. 
The disease is generally distributed throughout the world and affects 
all warm-blooded animals including man. The percentage of infected 
animals varies in different localities and as a rule is highest in the 
most thickly populated districts. Among dairy herds the percentage 
of infection is highest in the largest herds. It may vary from zero 
to 100 per cent, but may be estimated at from 15 to 50 per cent, 
depending on the size of the herd, the care which has been exercised 
in forming the herd, and the sanitary condition of the premises. In 
Germany, infection with tubercles among cattle slaughtered in public 
abattoirs varies from 6 to 46 per cent and similar data have been 
collected in this country. On account of the general use of the tuber- 
culin test in detecting this disease in its early stages, almost an unlim- 
ited series of data have been accumulated regarding the prevalence 
of tuberculosis, but the only point of value to be derived from a con- 
sideration of these data is that the disease is everywhere disseminated 
to an alarming and unexpected extent. In actual tests made in various 
parts of this country, the infection ranged from 2 to 60 per cent. 

The symptoms of tuberculosis are not characteristic and may easily 
be overlooked until during the later stages of the disease. ISTo help 
can be obtained in recognizing the disease from the general condition 
of the animal, since in many cases the external appearance remains 
excellent until within a few months before the general breakdown. 

On account of the uncertainty of the symptoms of tuberculosis, it 
has become necessary to apply the tuberculin test for the detection of 
the disease. This substance is made from pure cultures of tubercle 
bacilli and contains the toxin without the living tubercle bacilli. 
When innoculated into healthy animals, it causes no disturbance, but 



96 

in tuberculous animals it causes an elevation of temperature to the 
extent of 2 or more degrees Fahrenheit, accompanied with swelling 
at the point of innoculation, trembling, and other characteristic symp- 
toms. The great value of tuberculin lies in the fact that by its use 
we are able to detect the presence of tuberculosis in the earliest stages 
and before it would be possible to diagnose the disease from physical 
symptoms or by any other method. 

As soon as the disease has been recognized in a herd, it is necessary 
to take immediate action for its control. If only one or two ani- 
mals are affected and these are not especially valuable, it is perhaps 
best to destroy them at once and thoroughly disinfect the premises. 
If, however, the distribution of the disease is much greater in the 
herd, and particularly if the animals are very valuable, it is best 
to isolate all affected animals and keep them in buildings and on 
pastures from which healthy animals are excluded. The tuberculous 
cows may be used for breeding purposes for a number of years, since 
the disease is not inherited and their calves may be raised on the 
milk of other cows or on their own milk after previous sterilization. 
In this way considerable profit is derived from cows which otherwise 
would have to be destroyed. 

Various investigators in Germany, France, England, and the United 
States have worked on a system of vaccination for tuberculosis and 
have succeeded in perfecting it so far that cattle may be rendered 
temporarily immune to the disease by the application of this method. 
The method consists essentially in inoculating the young susceptible 
animal with tubercle bacilli of human origin. It is generally known 
that human tubercle bacilli are less virulent than those which come 
from cattle and are therefore comparatively safe to use for this pur- 
pose. The method is therefore essentially the same as vaccination 
for smallpox. A mild form of the disease is produced and persists 
for some weeks, after which the animal recovers and is immune to 
natural or artificial infection with tuberculosis for a few months. 
This method has been elaborated by von Behring, Arloing, McFad- 
yean, Pearson, and others. Quite recently Pearson has published the 
result of two years' experiments during which he tested this vaccina- 
tion method on young animals which were already infected with 
tuberculosis. It was found that five or six inoculations with human 
tubercle bacilli of low virulence caused the tuberculous, processes in 
the lungs and other organs to become inactive and surrounded with 
thick walls of connective tissue. The vaccination, therefore, appears 
to have a decided curative effect and may possibly be used in the treat- 
ment of the disease. 

Tumors. — This term is used to denote abnormal masses of tissue 
of a non-inflammatory and comparatively inactive nature and located 
in various organs of the body. In many cases tumors arise without 
anv obvious cause, appear to bear no relation to the nutrition of the 



97 

body, possess no physiological function, and are not easily classified 
from the standpoint of etiology. Different theories have prevailed 
regarding causes of tumors. They have been attributed to a peculiar 
predisposition, to mechanical or chemical irritation, to nervous in- 
fluence, and to the existence of minute animal or plant parasites in 
the tissue. Recently many announcements have been made regarding 
the discoveries of the micro-organisms of cancerous and other tumors, 
but such discoveries require further confirmation. In general, tumors 
are divided into the two classes of benign and malignant growths. 
Benign tumors should be removed if their presence renders the animal 
unsightly and therefore diminishes its value. They may be readily 
removed by surgical methods and the operation should not ordinarily 
be accompanied with any serious consequence. In the case of malig- 
nant, tumors, however, a cure may not be brought about by removal of 
the visible tumor since other foci of the disease may have already 
originated in other parts of the body. The treatment of malignant 
tumors must necessarily be left in the hands of veterinarians since 
successful results can not be expected from operations upon such 
growths by the ordinary individual. 

Verminous bronchitis. — Young cattle on wet meadows or marshy 
pastures, especially in locations which are subject to flooding from 
rivers, may become infested with a small round, worm known as 
Strongylus micrurus. This worm becomes lodged in the trachea, and 
bronchial tubes which it occurs in large numbers and causes an irri- 
tation and inflammation of the respiratory membranes. In cases of 
serious infestation, the trachea may be obstructed so as to choke the 
animal and cause death. The symptoms usually include a hacking 
cough which may appear in the form of paroxysms. Sometimes the 
parasitic worm may be observed in the mucus which is expelled. In 
treating this disease, affected calves should be placed in a clean, dry 
stable and subjected to fumigation with chlorin gas or sulphur fumes. 
The inhalation of these irritating gases causes violent coughing, as a 
result of which the worms may be expelled. Calves may also be 
treated by inserting a hypodermic syringe between the rings of the 
windpipe and injecting into the trachea a mixture of equal parts of 
turpentine and sweet oil to which a few drops of carbolic acid have 
been added. A mixture of olive oil and turpentine may also be used 
for the same trouble. In some infestations with this worm, however, 
numerous lines of treatment have been tried without any apparent 
success. Wherever the disease appears, it is desirable that calves be 
removed from low, marshy pastures in which the disease occurred and 
should be provided with better feed and. clean water in troughs. 

Warble fly. — This insect was at first confused with the European 
species but should really be referred to as Hypoderrmi lineata. The 
adult is a black fly thickly covered with yellowish hairs and about 
y 2 in. in length; there are two yellow and white bands on the body. 



98 

The eggs are laid on the back of cattle after which they gain entrance 
to the alimentary tract on account of the cattle licking themselves. The 
larvaB then hatch out and make their way through the walls of the 
esophagus and finally into the subcutaneous tissue along the back of the 
animal. This migration occupies several months. Immediately under 
the skin of the animal the larvas pass through several stages of growth 
finally attaining considerable size. Upon reaching full size the mag- 
got emerges from the skin and falls on the ground where it remains 
until the adult fly issues. The chief injury from this pest is done to 
the skin of the animal and in this respect the loss is considerable. In 
preventing the attacks of the warble fly the backs of cattle may be 
smeared with fish oil or kerosene. 

Wounds. — In cattle wounds seldom receive the attention which they 
deserve. While small wounds such as abrasions of the skin may not 
lead to serious consequences under favorable conditions they are always 
susceptible to infection with comparatively nonvirulent bacteria or to 
infestation with fly larvae. In such cases the wounds cause great irri- 
tation, loss of flesh, and diminution of milk yield. The possibility is 
always present, moreover, of infection of wounds with the organisms 
of tetanus or septicemia. It is highly desirable, therefore, that all 
wounds of the skin be immediately treated with a suitable antiseptic 
solution such as carbolic acid, corrosive sublimate, formalin, sulphate 
of zinc, blue vitriol, or nitrate of silver. In warm seasons it may be 
desirable to rub some repellent ointment upon such wounds in order 
to prevent flies from depositing their eggs. 



99 



CHAPTER IV. 

FEEDING DAIKY COWS. 

A few years ago a knowledge of the principles and practice of feed- 
ing cows would not have been considered among the educational 
requirements of the milk inspector. Now however the inspector is 
almost always asked for suggestions regarding feeding. The dairyman 
recognizes that feeding is the most important part of his business. 
The cow is properly looked upon as a machine for the transformation 
of feeds into milk. The regularity and continuance of the milk flow, 
and the quantity and quality of the milk depend upon the kinds and 
relative proportions of feeding stuffs in the ration. The dairyman's 
chief objective point is the production of the largest possible milk 
yield. To this end it is a duty of the milk inspector to give all possible 
assistance, for the milk producer's profits are none too large, and the 
inspector can suggest the improvement of sanitary conditions with 
better grace if he can also give some helpful advice. The following 
brief discussion of feeding cows is intended to be of help in the pro- 
duction of large quantities of standard milk. 

During the whole period of lactation the dairy cow should receive 
grain, succulent feed and dry roughage. No cow can be kept at her 
highest productive point without feeding liberal quantities of grain. 
The effectiveness and palatability of any ration of grain and roughage 
are increased by adding succulent feed. The comfortable feeling 
which induces restfulness and rumination on the part of the cow comes 
from a full stomach, which is achieved by feeding suitable roughage. 

Gbains for Cows. 

The most widely used and best grain feeds for milk production are 
bran, wheat, middlings, barley, brewers' grains, malt sprouts, buck- 
wheat bran and middlings, corn and its products (corn meal, gluten 
meal, feed, gluten flour, sugar feed, etc.), cottonseed meal, kafir corn, 
linseed meal, oats, peas, and spelt. 

Bran may be fed in rations of 2-6 or more pounds per day. It is 
highly palatable has a favorable effect upon digestion, and tends to 
tne production of a high quality of milk. The milk consumer can 
have no objection to its use to the full capacity of the cow. Bran is 
somewhat less effective than cottonseed meal. It may well be fed in 
combination with wheat middlings or corn meal. 

The best barley byproducts are barley sprouts and brewers' grains. 
Malt sprouts should be fed wet, and may constitute one third of the 
grain ration. They are equal in effectiveness to a mixture of oats and 
peas but slightly inferior to cottonseed meal. About 2 pounds daily 
is a suitable amount. Brewers' grains at the usual price are an eco- 



100 

nomical feed in rations of 10-15 pounds per day with corn meal. A 
good ration of dried brewers' grains is 2-5 pounds. Some dealers 
have raised objection to the use of brewers' grains on the ground that 
they injure the flavor of the milk, but as a rule no bad effect is noted. 

Buckwheat middlings are more effective than bran and corn meal, 
produce a firm butter, and milk of an excellent flavor. They may be 
mixed with other grains to the extent of 3 or 4 pounds per day. They 
are not always well relished when fed alone. 

Corn meal is more effective than whole corn but should not be fed 
alone. Better results are obtained by mixing it with a more nitro- 
genous concentrate such as bran, cottonseed meal or linseed meal. 
Corn meal may also be balanced by mixing with gluten meal or gluten 
feed. These latter produce milk of a good flavor but have a tendency 
to soften the butter fat. About 2 pounds per day is enough of either. 

Cotton seed meal is perhaps the most effective milk producer of all 
the grain feeds. It should be fed with caution, beginning with ^4 lb. 
per day and gradually increasing to 4-6 pounds. Cotton seed meal 
always hardens the butter fat but may give it a light color. It is 
easily balanced by mixing it with corn meal. When thus fed it always 
increases the milk flow. 

Distillers' grains are not very palatable and are objected to on 
account of the flavor of the milk. 

Kafir corn and kafir corn meal are about equal to corn and corn 
meal in every respect. The quality of the butter is sometimes not 
quite equal to that from corn meal. 

Linseed meal is an excellent laxative and its beneficial effects are 
seen in the glossy coat of the cows. It increases the milk flow and 
favorably affects the quality of the milk and butter. It may be fed in 
rations of 6 pounds but the best results follow the addition of 1 pound 
to an 8-pound ration of mixed bran and corn meal. 

Narrow and Wide Rations. 

Narrow and wide rations are short convenient terms used to denote 
the fact that the ratio of digestible protein to other digestible matter 
in the ration is wide or narrow. The figures taken in calculating 
nutritive ratios are based upon the heat value of the various constitu- 
ents of the ration. The heat value of fats is 2.4 times that of carbo- 
hydrates. In calculating the nutritive ratio of a given ration the 
amount of digestible fat multiplied, by 2.4 is added to the digestible 
carbohydrates and the sum divided by the amount of digestible pro- 
tein. The quotient is the nutritive ratio. The nutritive ratio of tim- 
othy hay is 1 :15.5 and is called wide, while the nutritive ratio of 
linseed meal is 1 :1.7 and is called narrow. If the dairyman wishes 
to compute the nutritive ratio' of various combinations of feeds he 
should have a table of analyses, showing the percentage composition of 
feeding stuffs. Such a table is given in U. S. Dept. Agric. Farmers' 
Bui. 22, which may be had for the asking. 



101 

Tt is evident from the above statement that narrow rations contain 
relatively more protein. The protein or nitrogenous matter in the 
ration is the most costly of all the constituents. Narrow rations are, 
therefore expensive. The practical point for the dairyman is to de- 
termine whether it pays to feed narrow rations. The necessary protein 
for the ration may be obtained by purchasing or raising bran, cotton- 
seed meal, linseed meal, wheat middlings, gluten meal, oats, peas, 
etc., or by the more extensive use of leguminous crops such as clover, 
alfalfa, field peas, cowpeas, soy-beans, vetches, etc. With ordinary 
roughage and succulent feeds corn meal would make a wide ration, 
Such a ration may be balanced or made narrower by adding some of 
the nitrogenous feeds just mentioned. If all the nitrogenous feeds 
have to be purchased at ordinary market prices it will not pay to 
make the ration too narrow. If on the other hand the protein in the 
ration is obtained from legumes grown on the premises a narrow ration 
may be prepared very cheaply. 

Narrow or medium rations are superior to wide rations for milk 
production. Wherever the experiment has been tried of narrowing 
the ration for cows which have previously received a wide ration, the 
result has been an increase in milk production. As a rule the in- 
crease more than counterbalances the extra cost of the ration. 

Size of the Grain Ration. 

The amount of grain fed daily to cows ranges from 2 to 15 pounds. 
The quantity of grain to be fed is by no means an indifferent matter. 
Only the best cows can profitably utilize the largest grain rations. For 
the average cow 8 pounds of grain should be the maximum. In fact, 
it requires a good cow to give profitable returns from 8 pounds of 
grain daily. This is largely an individual matter with each cow. If 
all grain feeds have to be purchased and the market price is high 
there is economy in reducing the grain ration. If on the other hand 
grains are cheap or are largely raised on the farm the grain ration 
should be put at the highest point of economic return. If a cow is 
receiving 2 pounds of grain and the grain ration is increased by 2 
pounds there is sure to be an increase in milk production. Likewise 
a diminution in a moderate grain ration will result in reducing the milk 
yield. For good dairy herds 6-8 pounds of mixed grains constitute a 
suitable ration. 

Succulent Feeds. 

A suitable amount of succulence in the ration may be obtained by 
the use of pasture, soiling crops, silage or roots. Pasture in good 
condition has the great advantage of furnishing green feed in the 
tender and most palatable stage. In grazing, cows get healthy exercise 
in the open air. Pasture has the further advantage of being the 
cheapest and easiest way to provide green feed. The disadvantages of 
pasture are worry from flies, garlic and other weeds which spoil the 



102 

flavor of the milk, shortage of grass from drouth, and exposure of 
cows to heat. The best pastures are those which are sown with culti- 
vated grasses. 

Soiling. — The soiling system has taken the place of pasture where 
land values are high. In this system the farm is divided into small 
fields which are planted to various forage crops so as to secure a suc- 
cession of green forage from May to November in the North and nearly 
the year around in the South. A system of rotation must be adopted, 
for most crops are at their best for only about 10 days. The best 
crops for soiling are alfalfa, red clover, crimson clover, cowpeas, field 
peas, soy-beans, corn, oats, rye, millet, kafir corn, sorghum, rape, teo- 
sinte, mixed grasses etc. While each crop is in its prime enough is 
cut for each feeding, hauled at once, and fed in a fresh state to the 
cows in the stable or in the yard. From three to five times as much 
forage is obtained by soiling from an acre of land as by pasturage. 
Less land is therefore required for a given number of cows. Soiling 
will impoverish the land if legumes are not sown at frequent intervals 
in the rotation. Legumes are the most valuable soiling crops, but corn, 
sorghum, teosinte, rye, and mixed grasses are very palatable and easily 
digested. There is considerable labor involved in operating a system 
of soiling. Rape is somewhat objectionable, for it may taint the milk. 
Tn estimating the necessary acreage of crops it may be expected that 
an acre of clover will carry 10 cows for 16 days, an acre of corn for 
the same length of time, an acre of cowpeas for 21 days and an acre 
of sorghum for 36 days. A cow will eat 40-60 pounds of green feed 
per day in addition to grain and hay. 

Silage. — Silage is fermented corn or other forage preserved in air 
tight structures known as silos. Silage ordinarily means the fer- 
mented corn plant (ears and stalks). Other plants are used for silage, 
such as clovers, alfalfa, sunflowers, sorghum, cowpeas, sugar beets 
etc. They may be ensiled alone or in combination with corn. Crops 
for silage may be harvested in rainy weather when it would be impos- 
sible to make hay. The chief advantages of silage are that the whole 
crop may be harvested at the time when it has attained its greatest 
weight of digestible matter, that the work of harvesting is less than by 
the soiling system or dry curing, and that it provides a supply of suc- 
culent feed in winter. It does not taint the flavor of the milk if fed 
after milking. The proper ration of silage is 30-35 pounds per day. 

Roots and fruits. — Succulence and palatability may also be added 
to the ration by the use of roots and fruits. Cull apples may be fed 
in rations of 15-35 pounds per day. Apple pomace, fresh or ensiled, has 
a favorable effect upon the quality of the milk. Artichokes and field 
beets are about equal to corn silage in milk production, but rather more 
expensive. No objection can be raised to carrots, but cabbage and 
mangels may have an undesirable influence upon the flavor of the milk, 
and the quality of the butter. Potatoes are inferior to corn silage but 



103 

have no specific bad effect upon the milk. Pumpkins may be fed to 
the extent of 40 pounds per day with good results. Turnips are an 
inferior root for cows and affect the odor of the milk. Sugar beet 
pulp is an excellent dairy feed. It may be fed in rations of 20-70 
pounds per day in addition to 6 pounds of hay and 6 pounds of grain. 
Milk from cows fed sugar beets or sugar beet pulp is of good flavor. 

Dry Roughage. 

The chief hay and other roughage crops for cows are alfalfa, 
clovers, cowpea, field pea, vetch, soy-bean, brome grass, corn, kafir corn, 
millet, oats, rye, sorghum and timothy. 

Alfalfa is highly nitrogenous and a very effective milk producer. 
It may be fed in rations of 20-40 pounds per day but about 15-30 
pounds is a better ration. A combination of alfalfa and corn meal 
is one of the cheapest rations which can be devised for dairy cows. 
By furnishing protein in the form of alfalfa or other legumes in place 
of purchased nitrogenous grain feeds a saving of 30 per cent is made 
in the cost of milk production. Milk and butter from alfalfa are of 
excellent quality. The only objection to alfalfa is its tendency to 
produce bloat, but cows may become accustomed to it so that no serious 
consequences result. 

Brome grass may be used to replace timothy or other hays. It is 
about equally valuable with timothy. It is not raised in large quanti- 
ties. There is no objection to its use. Clovers are worth about $15- 
$17 per ton for milk production. Bed, crimson and alsike clovers are 
about equally valuable, and may be economically used to replace nitro- 
genous grain feeds. Moldy clover hay is objectionable, otherwise 
clover is an excellent dairy feed. 

Corn stover is not as highly appreciated as it should be. If run 
through a cutter or shredder nearly all of it will be eaten by the cows. 
It is fully equal to the best timothy hay for cows. Corn fodder is 
equal to silage in digestible matter and about equally palatable. Well 
cured stover is an unobjectionable feed, and it seems strange that so 
much of it is allowed to go to waste in the corn belt. 

Cowpea hay is an extremely stimulating feed. It is coming more 
and more into prominence, and produces a good quality of milk. 
Soule found that with cowpea hay and cottonseed meal milk can be 
produced for 5 cents a gallon and butter for 10 cents a pound. In 
other experiments in Alabama cowpea hay showed a feeding value 
equal to that of bran. 

Salt marsh hay may taint the milk, and is not. a very effective feed. 
Kafir corn, fodder, lespedeza hay, millet hay, oat hay, serradella, tim- 
othy, vetch hay, wheat hay, and soy-bean hay may be fed to cows before 
or after milking without affecting unfavorably the quality of the milk. 
Soy-bean hay is a particularly effective milk producer. In rations of 
about 7 pounds in combination with cottonseed meal and wheat bran it 
greatly stimulates the milk flow. 



104 

Miscellaneous Feeds. 

From the feeding stuffs mentioned above suitable rations may be 
made up for dairy cows in any locality. Occasionally other miscel- 
laneous feeding stuffs are recommended for dairy cows. 

Proprietary feeds. — Farm papers and other periodicals continuously 
carry advertisements of various proprietary feeds. The manufac- 
turers claim that these feeds will increase the weight of the animal 
and also the milk yield, while improving the health of the cow. The 
numerous chemical analyses which have been made of these substances 
have shown conclusively that they contain well known chemicals and 
drugs which may be purchased at any drug store at a much lower 
price. The prices charged for proprietary feeds are exorbitant con- 
sidering their slight medicinal and nutritive value. If cows are fed 
well balanced rations of wholesome feeds, and if the rations are varied 
from time to time with proper regard to their relative proportions, 
the cows will not need condimental feeds. If loss of appetite, lack of 
condition, or disease arise, the matter should be investigated, a change 
made in the ration or proper medicines administered. 

Other feeds. — Diried molasses beet pulp may be fed in rations of 3 
pounds to replace an equal amount of bran. ]STo sanitary objection 
can be raised to it. Its feeding value is about $12 per ton. Feeding 
small quantities of bone meal to cows has the effect of slightly in- 
creasing the amount of phosphoric acid in the milk ash. If there is 
no other use for skim milk it may be fed to cows with good results. 
Cows may be fed sugar without harm but there is no' economy in the 
process. 

Salt. — A supply of a good quality of salt should be constantly ac- 
cessible to the cows. It may be given in the form of a granulated 
salt or in large chunks for licking. If salt is withheld the milk falls 
off perceptibly. 

Water. — Reference has been made to the water supply for cows in 
Chapter III. A constant supply should be provided, moderately cool 
in summer, and not ice-cold in winter. The quality of drinking water 
for cows should be as good as that used for household purposes. 

Sample Rations. 

The possible combinations of suitable feed stuffs into good rations 
for cows is almost unlimited. Perhaps the best compilation of actual 
rations used by dairymen in different parts of the country is that pub- 
lished by Woll in Bulletin 38 of the Wisconsin Experiment Station. 
This list contains 100 rations adapted for use particularly in the 
eastern, northern and western States. The following rations have been 
suggested for use in Oklahoma, Mississippi and other southern States. 

Ration 1. — Johnson grass hay, 13 pounds; cottonseed hulls, 15 
pounds; cottonseed meal, 3 pounds; wheat bran, 4 pounds. 



105 

Eation 2. — Cowpea hay, 15 pounds; corn silage, 40 pounds; wheat 
bran, 5 pounds. 

Eation 3. — Cottonseed hulls, 20 pounds; cottonseed meal, 4 pounds; 
wheat bran, 5 pounds. 

Eation 4. — Cowpea hay, 10 pounds; cottonseed hulls, 15 pounds; 
cottonseed meal, 3 pounds. 

Eation 5. — Cowpea hay, 10 pounds; bermuda grass hay, 10 pounds; 
wheat bran, 3 pounds; cottonseed, 6 pounds. 

Eation 6. — Bermuda grass hay, 18 pounds; cottonseed meal, 2 
pounds; wheat bran, 3 pounds; corn and cob meal, 3 pounds. 

Eation 7. — Cowpea hay, 15 pounds; cotton seed, 8 pounds; corn 
meal, 6 pounds. 

Eation 8. — Sorghum hay, 20 pounds; cowpea hay, 10 pounds; cot- 
tonseed meal, 3 pounds. 

Eation 9. — Alfalfa, 15 pounds; cottonseed hulls, 12 pounds; cotton- 
seed meal, 3 pounds. 

• Eation 10. — Crab grass hay, 15 pounds; cowpea hay, 12 pounds; 
cotton seed, 6 pounds. 

Ration for cows giving eleven pounds of milk per day: 

No. 1. Cottonseed, 9 lbs.; corn stover, 20 lbs. 

No. 2. Cottonseed, 4 lbs.; cottonseed meal, 1 lb.; corn meal, 3 lbs.; 
prairie hay 10 lbs.; corn stover, 10 lbs. 

No. 3. Cottonseed 6 lbs.; alfalfa hay, 16 lbs. 

No. 4. Cottonseed meal, 2 lbs.; corn meal, 4 lbs.; prairie hay, 15 
lbs. 

Rations for cows giving sixteen and one-half pounds of milk per 
day: 

No. 5. Cottonseed, 9 lbs.; prairie hay, 20 lbs. 

No. 6. Cottonseed, 9 lbs.; alfalfa hay, 16 lbs. 

Rations for cows giving twenty-two pounds of milk per day: 

No. 7. Cottonseed meal, 3 lbs.; corn meal, 10 lbs.; prairie hay, 16 
lbs. 

No. 8. Cottonseed, 6 lbs.; cottonseed meal, 2 lbs.; corn meal 5 lbs.; 
prairie hay, 15 lbs. 

Rations for cows giving twenty-seven pounds of milk per day: 

No. 9. Cottonseed, 3 lbs.; cottonseed meal, 4 lbs.; corn meal, 10 
lbs.; prairie hay, 10 lbs.; corn stover, 10 lbs." 

The kinds of green forage chiefly used in Hawaii are Para grass 
(Panicum molle), alfalfa, sorghum, 'cane tops, jack beans, cowpeas, 
vines of sweet potato, honohono (Commelina nudinora), banana butts, 
leaves of ti (Cordyline terminalis), corn stalks etc. In the dairy 
section of Glenwood, where the rainfall is more than 300 inches a 
year, honohono is perhaps giving better success than any other green 
feed. At Glenwood honohono appears not to carry the immature 
stages of the fluke worm as in many other localities. Recently the 
beginning cotton industry has added cotton seed to the possible grain 
feeds for the Hawaiian dairyman. Corn is also being produced in 
increasing quantities. Our most important home-grown grain feed, 
however, is the algaroba bean. This may be purchased for about 
$7.50 per ton, ungroundi, and is worth much more as compared with 
the price of other grains. It is fed in rations of 3 to 6 pounds per 
day. 



10G 



CHAPTER V. 

BUILDINGS AND PREMISES. 

Dairying is a special line of animal industry in which the sanitary 
requirements are much more severe than in other related lines. These 
requirements do not begin merely with the product but extend also 
to the cows, the stables and the whole surrounding premises. The 
business fits in well with other branches of farming and as a rule some 
other line is carried on simultaneously in order to 1 utilize most profit- 
ably all the products of the farm and the byproducts of the dairy. 
Business and sanitary considerations in dairying, however, are not 
always identical. Hogs and chickens give excellent returns for the by- 
products of the dairy but no other animals should be kept in the same 
stable with cows. Such buildings must be separated from the dairy 
barn. 

Stables. 

It obviously lies outside the purpose of the present volume to enter 
into the structural details and architectural consideration of dairy 
buildings. The only standpoint from which we can discuss these 
matters is that of sanitation. In any thorough system of inspection 
the milk inspector must visit the producer from time to time and pass 
upon the general conditions which he finds there. In order that this 
inspection may proceed without friction and accomplish the intended 
results it is desirable that the dairyman and inspector should look at 
the problem from as near the same viewpoint as possible. The in- 
spector will then better appreciate the farmer's difficulties and the 
farmer will get a clearer idea of what is involved in the production of 
clean milk. 

The first consideration in the construction of a stable for dairy cows 
should be the cleanliness and ease of cleaning. The stable should be 
so located as to permit of thorough drainage and thus prevent undue 
dampness. It should preferably face the east and south or at least the 
windows should be chiefly on these sides in order to admit a maximum 
amount of sunshine at all times, and heat in winter. If the location 
of the stable admits of providing it with a supply of good running 
water, so much the better. 

The only satisfactory material for the floor of a cow stable is cement, 
Wood rots and absorbs odors. Brick and stone allow the accumulation 
of filth between one another. Cement concrete is the most durable of 
all materials for floors, is without odors, may be laid smooth enough 
to be easily cleaned without being too slippery for the cows to walk 
upon, and is impervious to water. It may therefore be cleaned at 
intervals by flushing with water. 



107 

The platform on which the cows stand should be 4^-5 feet wide, 
depending on the size of the cows. The width should be such that 
the cows do not have to stand with their hind feet in the gutter. A 
gentle and uniform slope of the platform toward the gutter brings 
about a satisfactory drainage. The manure gutter may be 14-16 
inches wide, 8 inches deep on the side next to the cows and 6 inches 
on the opposite side. The space allowed for each cow varies among 
dairymen from 3 to 4 feet, A space of three feet is rather narrow 
unless the cows are small. If the cows are gentle no partition between 
them is required. There is an advantage in an iron bar, however, in 
that the cows are thereby prevented from turning sideways and soiling 
the bedding and the other cows. The simpler the partition the better, 
for it is easier to clean. Similarly with mangers, if they are of too 
complex construction they are difficult to clean and food is often left 
in the corners to sour. It is really not necessary to have mangers and 
many dairymen prefer to build their stables without them. If man- 
gers are used they should have rounded corners and no crevices to hold 
dirt. A slight concavity in the cement in front of each cow with an 
opening in the center for flushing out serves the purpose of a manger. 
If the cows are dehorned and gentle as they should be there is no need 
of partition between their heads. The feeder is supposed to be present 
when the cows are eating so as to prevent them from stealing one 
another's feed. 

In some stables, in place of the usual manure gutter, there is merely 
a drop of eight inches behind the cows and the concrete slopes gently 
upward to the wall of the stable. The advantage claimed for this 
method of construction is that the manure is more easily removed 
and the whole readily flushed. The slope should not be steep, other- 
wise the cement will be slippery for the cows. The floor should meet 
the wall in a concave turn and without a sharp corner. 

The modern cow stable is a long structure designed for accommo- 
dating two rows of cows. Whether or not the rows of cows should 
face each other or the outside wall is a matter for each dairyman to 
determine. From a sanitary standpoint there is little or no preference. 
Tn one case the feeding passage is through the center of the stable and 
the manure is removed by two passages along the walls of the stable. 
In the other case the manure passage is in the center and the cows 
are fed by two passages next to the walls. The relative advantages 
of these two methods will appeal differently to different dairymen. If 
the soiling system of feeding is adopted it is convenient to have a drive- 
way through the center of the stable so that the green feed may be 
thrown in front of the cows directly from the wagon. According to 
the alternative scheme of construction there would be only one manure 
passage and the manure could be loaded directly into the wagon. In 
such a stable, if of great length, the feed can best be delivered to the 
cows from bucket carriers running on an overhead track. This track 
may connect with the silo at the end of the stable. The manure may 



108 

be removed by wheelbarrow or by bucket carriers and dumped into a 
manure pit outside of the stable or into the wagon to be hauled away 
daily or every other day. 

An outside width of 36 feet is sufficient for a stable to accommodate 
two rows of cows. The length will of course vary according to the 
number of cows. The strictly sanitary stable is not supposed to be 
used for any other purpose than as a permanent or temporary restraint 
for the cows. Some dairymen use one stable merely for milking. In 
this the construction may be cheap except the cement floor. The chief 
advantage of separate milking stables is that they may be kept well 
ventilated so that the odors of cows and manure are present only to a 
minimum extent, If stables are to be used for the permanent housing 
of the cows, they must be cleaned frequently. They are supposed to 
be only one story high and since they are not to be used for containing 
hay or other feed the dust problem is largely eliminated. The milk 
room is supposed to be separate from the stable and to be used for no 
other purpose. This is to avoid the absorption of odors by the milk. 

If the ceiling is 9 feet high this will give ample air space for the 
cows. The ventilation of stables is a matter about which the greatest 
difference of opinion has prevailed. The question is by no means 
settled and cannot be considered at length in this connection. We are 
interested in ventilation in this discussion only so far as it affects the 
odors of the stable and the health of the cows. Obviously the more 
rapid the change of air in a stable the less disagreeable will be the 
odors. For this purpose it is better that the foul air be removed from 
near the floor rather than from the ceiling. The products of respira- 
tion and animal metabolism are near the floor, while the warm air is 
at the ceiling. If, therefore, fresh air is let in high up on all sides of 
the stable and foul air is discharged from near the floor, the odors and 
respiratory products will be removed with a minimum loss of warmth. 
JNio system of artificial ventilation will operate unless the stable is 
constructed tightly and the currents are controlled. If the air leaks 
in freely around the doors and windows it will obviously interfere 
with the intended movement of air in the ventilation shafts. Since a 
loosely constructed stable needs no artificial ventilation and since an 
artificial system is of no value except in a practically air-tight stable 
the question has been raised by many dairymen how much attention 
should be given to the matter of ventilation. 

In summer the ventilation of any stable is a simple matter. In 
winter, however, there is the question of heat to consider. Here again 
we have a wide divergence of views. On the one hand, it is advocated 
that the temperature of the stable even in the coldest weather should 
not fall blow 50-60°F. If this temperature is maintained without 
artificial heat it is necessary that the change of air be so regulated that 
the animal heat of the cows will keep the air of the stable at the de- 
sired temperature. Theoretically there seems to be no objection to this 
plan, but if cows are kept according to it they become very susceptible 



109 

to cold and are likely to suffer if for any reason they have to be turned 
outdoor in winter. 

The whole question of the optimum temperature for cows is in con- 
troversy and nothing would be gained, therefore in attempting to settle 
the matter at this time. Professor Fraser at the Illinois Experiment 
Station investigated the problem thoroughly and came to the conclu- 
sion that cows do well in open covered sheds even in the coldest 
weather of winter. Keeping cows in a stable continually and under 
approved sanitary conditions involves a great deal of work and careful 
attention to each individual cow. Those dairymen who allow their 
cows the freedom of a shed or covered barnyard and use the stable 
only for milking are well pleased with the system. In reply to a 
circular letter sent to them by Prof. Fraser they stated in essential 
uniformity that the method saves labor in cleaning the stable and iu 
feeding roughage, keeps the cows more comfortable and preserves the 
manure in better condition by reason of the greater amount of bedding 
used. One dairyman reports that "the system is good only where 
straw is abundant that can be so utilized. If the straw is limited in 
amount the system would be filthy and if the herdsman is negligent 
or careless the cows will become more or less filthy. With a careful 
man and a reasonable attention the system works exceedingly well." 
.Another farmer states "our cattle are cleaner than any herd of stalled 
cattle I ever saw. A soiled cow is a rare sight in our herd. By this 
method we have increased milk yield and greater healthf ulness ; have 
not had a case of milk fever since our dairy started." 

The excellent reports made on this system by various dairymen led 
Prof. Fraser to test the scheme at the University dairy. A shed 30x68 
feet afforded abundant room for 22 cows which were very satisfactor- 
ily cared for in this manner. From the test the following conclusion 
was drawn : "It has been found that the cows keep much cleaner than 
when stabled and that the milking stable is in a much more sanitary 
condition, consequently it is easier to produce clean milk. By this 
method there is less difficulty in providing cows with an abundance 
of fresh air and they are more vigorous and healthy and have better 
appetites than when kept in a stable. Since they can move about and 
get exercise they will not suffer in cold weather if the temperature is 
somewhat lower than in the ordinary stable." The great saving in 
labor and in fertility of the manure is enough to highly recommend 
this method so long as there are no sanitary objections. The increas- 
ing complexity of inspection systems puts increasing burdens on the 
dairyman and raises the price of milk. The limit will soon be reached 
beyond which the ordinary milk consumer can not go. Any sanitary 
system, therefore, which at the same time reduces the cost of produc- 
tion must be looked upon with favor. 

As already indicated the approved sanitary stable is only one story 
high and used for no other purpose than milking. Some large city 
milk dealers will not. accept milk unless these conditions are complied 



110 

with. These requirements are made, however, on the assumption that 
the farmer will not exercise any care in overcoming the insanitary 
conditions of his farm. This is true of some farmers but not of all. 
In all systems of sanitary improvement and reform the best and most 
reliable results are obtained only when the men concerned are induced 
to take a direct and personal interest in the matter. It must be ad- 
mitted that there are d.airymen who produce milk of excellent quality 
under conditions which would yield doubtful results in the hands of 
a careless man. 

The vast majority of dairy stables throughout the country are built 
in connection with a cow barn which is also used for the storage of 
feed. A favorite type of such barns has the cow stable in a basement. 
Clean milk can be produced in these stables provided the walls and 
ceiling are tight, the floor impervious to water, the feedi delivered to 
the cows without raising a. dust and the stable cleaned in a satisfactory 
manner. Many, at present, highly insanitary dairy stables could be 
immensely improved and rendered passable by putting in more win- 
dows, a cement floor and whitewashing the walls and ceiling. It is 
unnecessary to discuss this point further. The intelligent dairyman 
knows the stable conditions which allow the production of clean milk. 
In the interest of the public the milk inspector has the right and duty 
to insist upon these conditions being met, by the dairyman. Unreason- 
able requirements in stable construction should and will not be made, 
but the dairyman who wishes to continue in the business at a profit 
may as well meet the reasonable demands of the milk-consuming public 
as promptly as possible. Clean milk can not be produced in dark 
stables, on a moist poorly drained foundation, with rotten manure- 
soaked wooden floors. All such conditions can be readily remedied 
by the intelligent dairyman, and no other kind of a dairyman has the 
right to furnish milk to the public. 

Bedding. 

The choice of bedding is a matter of considerable importance to 
dairy farmers. A good bedding material should be easily distributed, 
keep the cows comfortable, remain in place, absorb the liquid manure, 
and should add no dust to the stable. Perhaps the most thorough 
comparative test of the value of different substances for bedding has 
been made by Professor Doane. A comparison was made between 
cut and uncut wheat straw, cut corn stover, sawdust and shavings. 
When cows were kept in the stable 16 hours per day it required 2.3 
lbs of whole straw and 2.9 pounds of cut straw daily per cow to keep 
them clean and make them comfortable. Cut straw was too easily 
kicked about, became unevenly distributed on the floor and packed 
down too solidly for comfort. Whole straw proved superior to cut 
straw and under the conditions named only 1800 lbs. were required 
per year per cow as compared with 2300 lbs. of the cut stray. Stover 
cut with a silage cutter also compared unfavorably with whole straw, 



Ill 

3.2 lbs. daily being required per cow. Except in the amount required, 
however, it proved to be a better bedding than straw. It kept the cows 
cleaner and staid in place better. It may well replace wheat straw 
for bedding to a large extent. Sawdust and shavings were found to 
be ideal materials for bedding. They are as nearly dustless as any 
bedding can be, keep the cows exceedingly clean and make the manure 
easy to spread. Nothing can compare with sawdust or shavings in 
giving a cleanly appearance to the stable. Sawdust can not be con- 
veniently obtained except in the vicinity of sawmills, but in such 
localities it is the cheapest bedding. In Doane's test the annual cost 
of bedding per cow stabled 24 hours per day ranged from 45 cents on 
sawdust to $4.82 on cut wheat straw. 

Baknyakds. 
The yards about the stable need intelligent care to prevent them 
from becoming filthy and unsanitary. If the soil in the barnyard is 
not unusually well drained it is sure to be muddy especially in the 
spring. This may be largely obviated by a covering of gravel or 
cinders, or still better by paving with brick. If the last method is 
adopted the yard is easily cleaned. The improvement of conditions 
about barnyards is often objected to on the ground of the expense in- 
volved in the undertaking. It is a necessary expense, however, on 
every approved dairy farm. Without dry well drained yards it is 
impossible to keep the cows clean. The covered sheds referred to 
above are a part of the yard and must be plentifully supplied with 
bedding. The more bedding the more completely is the liquid manure 
absorbed and the less work in cleaning the cows. Yards from which 
the manure is removed only once per year are unspeakably filthy and 
cause a great amount of extra work in cleaning the cows. Further- 
more the fertility of the manure is in great part lost. 

Disposal of Sewage. 

One of the most important points in the sanitation of every dairy 
farm is the method of disposal of sewage. The stable may be thor- 
oughly cleaned, the cows carefully groomed, the feed stuffs above crit- 
icism and the milk utensils in approved condition, and yet the manner 
of disposing of sewage may be such as to make it impossible for the 
inspector to approve the premises as a whole. One of the greatest 
dangers in this connection is that the water supply may become con- 
taminated. If such is the case all other sanitary precautions come to 
naught. Water used in washing milk utensils must be above suspicion. 
Some of the worst outbreaks of typhoid fever ever reported were 
traced directly to contaminated water used in cleaning the milk vessels. 
Moreover there must be a clean supply for the household and for the 
cows. In order to secure this the water must be protected so that no 
sewage comes in contact with it by seepage through the soil. 

Many systems of sewage disposal have been proposed and one of 
the best is that suggested by Prof. Erf of the Kansas Experiment 



112 

Station. This system is designed to take care of the sewage from the 
house, stable and milk room. The manure gutter in the stable, the 
waste pipe from the milk room and the kitchen and closet in the house 
are all connected by means of sewer pipe with a septic tank, conven- 
iently located to receive all this drainage. If the slope of the ground 
will permit it is best that the tank be placed below the level of the soil 
to avoid freezing in winter. Otherwise it must be covered for protec- 
tion. The septic tank should have two' to four compartments so as to 
insure the thorough liquefaction and dissolution of all waste material. 
This decomposition is brought about by the action of bacteria and 
results in a fluid sewage from which the disagreeable odors have been 
largely removed. The process of decomposition is greatly furthered 
by the presence of large quantities of water. On dairy farms an 
abundance of water is used in washing the milk utensils and in flushing 
the stable. 

In the sytem proposed by Prof. Erf the septic tank daily receives 
liquid manure and other forms of fluid sewage. An outlet must there- 
fore be supplied for the sewage to be discharged from the tank after 
thorough liquefaction. The sewage is to be distributed on the neigh- 
boring parts of the farm either by surface irrigation or by a system 
of sub-irrigation pipes. Since there will be a constant discharge of 
liquid sewage it is necessary that in winter it be carried in pipes below 
the line of frost. For this purpose the ordinary porous tile is used. 
A main line of four-inch tile and laterals of three-inch tile will carry 
the sewage. It is suggested that one portion of the. farm receive the 
sewage in summer and another in winter. The tile for use in summer 
need not be laid deeper than 8 inches in the ground. 

By this sytem the soil is fertilized and irrigated, at the same time. 
If the soil thus treated be devoted to intensive farming or market 
gardening, the annual increase in productiveness will pay the total cost 
of installing the sewage plant. The tank should be constructed of 
brick or concrete, and for the ordinary farm a tank 10 feet square and 
four feet deep will be sufficiently large. 

The disposal of farm sewage by the method just described should 
eliminate nearly all danger of pollution of the well water. Neverthe- 
less some additional thought must be given to this matter. It is 
generally known that water which filters through several feet of soil 
is practically free from contamination. The well must therefore be 
so constructed that no impurities can gain entrance to it either from 
the top or the sides. This may be accomplished by making the wall 
water-tight down to the level of the water. 

Milk Rooms. 

In the plan proposed by Pearson for the improvement of market 
milk the following suggestions are made regarding milk rooms: 
"There shall be a room which shall be used for no other purpose than to 
provide a place for handling the milk, storing clean milk utensils, and 



113 

holding fresh milk previous to its removal from the dairy. It shall 
be within easy access of the stable, but so placed that it can not easily 
be reached by du=?t or odors from the stable or yard or other sources. 
Tf under the same roof with the stable it shall be separated therefrom 
by a light, clean and ventilated room or passageway at least 4 feet 
wide and 4 feet long with doors kept closed by springs. Or the ar- 
rangement shall be such that it shall be necessary to pass out-of-doors 
in going from the stable to the milk room. 

This room shall be entered only by persons having business therein ; 
no one shall be admitted who has been where a contagious disease 
exists or who is wearing dirty garments. It shall be kept scrupulously 
clean and shall be occasionally thoroughly dried in all its parts. It 
shall contain nothing that is not required for handling milk. Dairy 
utensils shall be removed to another room for cleaning as soon as they 
have been used. Sour milk shall not be left in the milk room. It shall 
be well lighted. Windows and doors shall be fitted with screens to 
keep out insects. It shall have a hard floor, impervious to moisture. 
The drain shall be provided with a common S-trap, and so constructed 
that it can be easily cleaned by steam or disinfectants. Except under 
unusual conditions the drain shall be at least 200 feet long. TSTo per- 
manently moist place, except running water, shall be allowed in its 
vicinitv. The walls and ceiling shall be kept clean and light colored. 
If whitewash is used,, a fresh coat shall be applied at least every three 
months, or oftener if necessary, to keep the walls clean. Spots of mold 
shall not be allowed to develop on the walls. If there are shelves of 
wood in the room, they shall be painted or oiled. ~No accumulation of 
dirt, cobwebs, rubbish, or unclean materials shall be permitted." 

Not every dairy farmer will have an ideal milk house. It is not 
necessary that it be an elaborate or expensive structure, for satisfactory 
cleanliness may often be brought about in an economic manner. The 
milk house may be built over a natural spring and the dairyman may 
depend upon the spring water for cooling the milk. In other cases the 
milk room may be attached to the stable or the dwelling house, or may 
be a separate building with ice house attached. The only essential 
point is that it be so constructed as to admit of easy and thorough 
cleaning. ISTo other operations should be allowed in the milk room 
which might in any way contaminate the milk. In other words the 
milk room is maintained for the purpose of mixing, straining, aerating, 
cooling and storing the milk. It may be constructed of wood but the 
floor should be concrete. 

In connection with the milk room there should be a wash room in 
which all dairy utensils are to be cleaned. It should be provided with 
hot and cold water and steam, if possible. The shelves on which the 
utensils are set to dry should be before windows admitting an abund- 
ance of light. On the vast majority of farms the milk utensils are 
washed by farmers' wives and set on outside shelves to dry in the 
direct sunlight. This method is fairly satisfactory except on dry 



114 

windy days when the air carries considerable dust. Milk utensils 
sitting out to dry are familiar sights on dairy farms, but special wash 
rooms are to be preferred from a sanitary standpoint and in the long 
run are cheaper and save much drudgery to the women folk of the farm. 

Inspection of Buildings and- Premises. 

The inspection of dairy premises is one of the most important parts 
of any official system for safeguarding the health of the milk-consum- 
ing public. It is at the farm that most opportunity is offered for the 
contamination of milk. The cows may become diseased, the stable foul 
and insanitary, the milkers affected with a contagious disease or in 
contact with such a disease, or the method of sewage disposal may be 
entirely at fault and the water become polluted. Moldy or otherwise 
unhealthy feed may render the milk secretion abnormal, and finally 
carelessness in handling the milk may enormously increase its dirt 
aril bacterial content. 

The inspection of the dairy herd and premises should be made by 
a competent veterinarian with some knowledge of sanitary engineering. 
Such an inspector is prepared to recognize and deal promptly with any 
diseases which may be present in the herd. The tuberculin test should 
be applied at not longer intervals than six months, in fact the. pro- 
gressive dairyman insists upon this precaution as a means of self 
protection. The milk of tuberculous cows can not be safely used as 
food for man or animals without previous sterilization. Tuberculous 
cows must be at once separated from the rest of the herd and never 
aliowed to come in contact with them again. There are also a number 
of diseases which temporarily render the milk unfit for use. In this 
list all forms of mammitis or garget stand at the head.. In cases of 
inflammation of the udder the milk becomes abnormal, contains exuda- 
tions sometimes of a hemorrhagic nature, and pus, and in some in- 
stances may carry pathogenic bacteria from lesions in the cow. These 
matters are discussed in the chapters on Hygiene and Diseases of 
Cows and on Transmission of Infectious Diseases, and need not be 
referred to at greater length in this connection. Any disease during the 
progress of which the cow shows an elevation of body temperature 
renders the milk unfit for use. 

In addition to the health of the cows the inspector will also take 
note of the thoroughness of grooming as evidenced by the cleanliness 
of the cows ; the condition of the stable with reference to construction, 
cubic space per cow, ventilation, lighting material used in construc- 
tion, sewage disposal, bedding, removal and storage of manure, and 
kind, storage and quality of feeding stuffs. He will also observe 
whether horses are kept in the same stable and whether all parts of the 
stable are thoroughly cleaned. 

Furthermore the inspection of the premises must also include an 
examination of the water supply for watering the cows and for wash- 
ins the milk utensils. In the examination the distance of the water 



115 

supply from the stable and possible sources of pollution will receive 
chief attention. Observations will be made on the condition of the 
milkers, utensils, care of the milk and every operation and feature of 
the farm which can in any way influence the character of the milk. In 
conversation with the dairyman the inspector will learn his attitude 
toward the question of improvement of the milk supply. The last 
point is of considerable importance, for the intelligent dairyman can 
produce sanitary milk under conditions in which the careless man 
would fail. 



116 



CHAPTER VI. 

MILKING AND THE HANDLING OF MILK 

As should be evident from a moment's consideration, the greatest 
opportunity for the contamination of milk is found on the farm in con- 
nection with the milkers, the cows, methods of milking, care of dairy 
utensils and the care of milk in preparing and transporting it to the 
customers. The major part of the responsibility for the production of 
pure milk, therefore, rests with the dairyman himself. This does not, 
however, relieve the consumer of all responsibility, for it is easily 
possible for the milk to become contaminated by unhygienic treatment 
after it is received in the house of the consumer. The undesirable 
changes which may take place in milk occur more rapidly after the 
milk is delivered to the various houses of the milk route if no especial 
care is taken to keep additional dirt and bacteria from falling into it 
and if no attempt is made to cool the milk to' a temperature at which 
the ordinary milk bacteria, will not multiply. 

Health and Habits of Attendants. 

One of the first considerations in the production of sanitary milk is 
the health and personal habits of the milkers and attendants of the 
cows. If these men are affected or come in contact with other persons 
who are affected with contagious diseases, the virus of these diseases 
may become attached to the hair or skin of the cows and may thus 
gain entrance to the milk, or the virus may pass directly from the 
hands or clothing of the milker to the milk or milk utensils. Atten- 
tion has frequently been called to the fact that it is impossible to lay 
too much stress upon the condition of the milker. As stated by Mar- 
shall, if the milker is an individual who. is naturally clean and particu- 
lar about his personal habits, the milk will be as satisfactory from a 
hygienic standpoint as can be produced under the conditions which 
prevail at the dairy. If on the other hand the milker is untidy and 
has filthy habits it is impossible to predict what kinds or amounts of 
filth and contamination may find their way into the milk. 

Much has been written by way of calling attention to this point and 
yet its importance has been greatly underestimated by many of the 
less progressive dairymen. ITncleanliness and filthy habits are not 
tolerated in a cook or in any person who has to do with the preparation 
and serving of any of our other kinds of food. Nevertheless milk is 
often produced in stables and under conditions in which it is abso- 
lutely impossible that a clean article could be obtained. Moreover, 
milk is more susceptible to contamination and dirt than most of our 
other articles of food and after it has become contaminated with dirt 
and bacteria it undergoes fermentative changes and deteriorates more 
rapidly than any other articles of diet 



117 

The progressive dairymen throughout the country have clearly 
realized the importance of this matter and insist upon cleanliness of 
clothes, hands and person in all milkers. It is recognized that there 
are almost innumerable operations which occupy the farmer's time 
and energies, but dairying must be considered a special industry, re- 
quiring special attention to sanitary details. While it may be trouble- 
some to put on a fresh suit of clothes at milking time, used for no other 
purpose, this is commonly considered as a necessary factor in the pro- 
duction of sanitary milk. If the dairyman has only a few cows and 
is fully alive to the necessity of sanitary precautions in the care of 
milk it may not be necessary to insist upon the use of a special suit for 
milking. If on the other hand dairying is engaged in as a business, 
the exclusive use of milking suits at milking time must be required. 

Not only must the suits which the milkers wear be clean and uncon- 
taminated but it is also necessary for them to give particular heed to 
the condition of their hands. Any dirt or bacterial contamination on 
the hands may readily gain entrance to the milk during the process 
of milking. In fact it is almost impossible to prevent such an occur- 
rence if the hands are not properly cleaned. It is only necessary to 
call to mind innumerable ways in which the hands of the attendants 
of a dairy stable must become contaminated in doing their ordinary 
work. Therefore it seems unnecessary to call attention further to< the 
necessity of a careful cleansing of the hands before milking the cows. 

If it seems too great a hardship' to make a complete change of out- 
side clothes before milking, it may be satisfactory to use a long cotton 
coat, which may be cleaned at frequent intervals and put on over the 
other clothes at milking time. 

It is not only necessary that the milker should avoid coming in con- 
tact with anyone suffering from an infectious disease, but he should 
also be in good health, or at least free from any contagious disease. In 
this connection the greatest danger occurs in the case of men who begin 
to milk cows too soon after convalescing from some contagious disease. 
It is well known that contagion may persist on the hands or in other 
parts of the body for considerable periods after the individual has 
regained his health. Thus in scarlet fever the process of desquamation 
may be delayed unusually long, particularly on the hands, and small 
parts of the skin containing the virus of scarlet fever may be rubbed 
off the hands and fall into the milk. Again, in typhoid fever, the ba- 
cilli persist in a virulent form in the urine and other excretions of 
the body sometimes for months after recovery from the disease. Wher- 
ever this is the case it is possible for such an individual to contaminate 
the milk unless the point is kept distinctly in mind. After the occur- 
rence of diphtheria the bacilli do not remain in the throat for so long 
a period, but it could easily occur that persons could feel well enough 
to milk cows before the contagion had entirely disappeared from the 
throat. If such should be the case the diphtheria bacilli might easily 
be thrown into the milk by coughing. The same is true of cases of 



118 

tuberculosis. No tuberculous individual should under any considera- 
tion have anything to do with milk. The bacilli are readily thrown in 
coughing and some of them would gain entrance to the milk, while 
others might -contaminate the stables. From this contamination cows 
might become affected or the bacilli might subsequently gain entrance 
to the milk in the stable dust. 

Moore has called attention to the fact that a large number of epi- 
demics of typhoid fever, diphtheria, scarlet fever and measles have 
been traced directly to the milk supply and in a considerable percent- 
age of these cases an explanation of the infection was found in the pres- 
ence of the contagious disease among the milkers or in their homes. 
Dairymen should remember that a quarantine in case of the prevalence 
of such diseases should not be confined merely to the avoidance of 
contact with susceptible individuals but should also extend to a protec- 
tion of the milk supply. 

In the plan for the improvement of market milk suggested by Pear- 
son the following rules are laid down regarding the milkers : 

"Before commencing to milk the milkers' hands shall be carefully 
washed, using soap and nail brush, and then rinsed in clean water. A 
special set of clean outer garments of white cotton or linen and cap 
shall be worn during milking and at no other time; when not in use 
these must not be kept in the stable or living room but in a clean and 
ventilated place." 

Every dairyman knows that some milkers are far more successful 
in securing clean milk than are others. It has frequently been observed 
that some of the men who milk cows in large dairies always bring to 
the milk room milk which is reasonably clean, although the general 
conditions of the dairy are not favorable for the production of hy genie 
milk. Stocking has called attention to' the desirability of noting the 
personal habits of men before hiring them to attend cows. A com- 
parative test of the bacterial content of milk showed a great variation, 
which was due to the care observed by different milkers. Thus the 
number of bacteria per c. c. of milk varied from 388 to 6150 in a 
test in which all the conditions were the same for the different milkers. 
All of the milkers were required to follow the same course of procedure 
in this test. The care with which instructions were carried out, how- 
ever, was obviously very different, in different men. As a rule the 
dairy students at the Connecticut Agricultural College were much more 
effective in preventing the contamination of milk than ordinary men 
hired to milk the cows. For example, the average number of bacteria 
per c. c. in milk drawn by students wias 914 as compared to 2846 
in that drawn by ordinary milkers. It is obviously a matter of the 
conscientiousness of the individual milker. A long and perfectly sat- 
isfactory set of regulations may be drawn up and posted in the dairy 
stable and all the milkers may be compelled to follow these instructions. 
Nevertheless it is possible to follow them in such a. perfunctory way 
that the desired results are not attained. It is also obvious that a 



119 

milker by the exercise of common sense and the most obvious sanitary 
precautions may produce milk of satisfactory quality. 

Cleanliness in Milking, Cleaning Cows, etc. 

In milking cows to obtain pure milk, attention should first be given 
to the condition of the cows. The hair and skin of the cows may be- 
come contaminated with all kinds of filth, particularly manure and 
the other dirt or dust of stables and yards. All of this naturally con- 
tains an unusually large number of bacteria which will influence the 
keeping quality of the milk, although they may not render it patho- 
genic. The most obvious way of preventing the manure and other 
filth on cows from gaining entrance to the milk is to clean the cows 
thoroughly 1 before milking. A thorough grooming and brushing, 
however, may not be entirely satisfactory. This process will remove 
the coarser particles of filth but will loosen up finer particles which 
readily fall from the hair during milking as a result of the movements 
of the cow or rubbing the arms of the attendant against the hair of 
the cow. The most satisfactory way of preventing this fine dust from 
falling into the milk is to moisten the udder and those portions of 
the cow from which the dust could readily fall into the milk. 

In a test at the Storr's Experiment Station ten cows were divided 
into two lots of five each, one lot receiving no especial care before 
milking, while the other five cows had the flank and udder wiped with 
a moist cloth, without using any antiseptic. In this test it was found 
that the average number of bacteria per c.c. of milk from cows which 
had been wij3ed with a damp cloth' was 716 as compared with 7058 
from cows which had not been treated. The highest number of bac- 
teria in any sample of milk from cows which had been wiped was 
8025, while in the case of one cow which had not been wiped the 
number was 15,475 and in another 64,590. These results call atten- 
tion sharply to the value of taking this precaution of wiping cows with 
a damp cloth before milking. It prevents the contamination of the 
milk with such enormous numbers of bacteria. 

While the general benefit of properly cleaning cows is almost uni- 
versally recognized, it is not desirable to brush the cows at milking 
time or immediately before milking. Attention has already been 
called to the fact that the hair and skin of the ordinary cow carry a 
large number of bacteria in the filth which becomes lodged on these 
parts. If this material is in a dry dust form, brushing just before 
milking sets it floating in the air, from which it may gain entrance 
to the milk. Thus in a test of this matter at the Storr's Experiment 
Station the average number of bacteria per c.c. of milk from cows 
not brushed at milking time was 1207 as compared with 2286 from 
those which were brushed at this time. The operation of grooming 
should obviously be done some time before milking or afterward. 

In connection with the danger of contamination of the milk from 
dust loosened from the hair and skin of the cows, it should also be 



120 

remembered that feeding hay just before or at milking time also 
adds greatly to the dust in the atmosj)liere of the stable. Corn stover 
and other dry feeds should also be withheld from the cows at milking 
lime. In Pearson's proposed plan for the improvement of milk it 
is recommended that "milch cows shall be groomed not more than 
one hour before every milking. A stiff brush shall be used to remove 
dry matter and places soiled with fresh manure shall be cleaned by 
washing. Long hair on the udder and flank shall be clipped." 

The suggestions made above regarding the cleaning of cows seem to 
be highly desirable when we consider the condition of the udder and 
flanks of dairy cows on premises where no special attempt is made to 
keep them clean. It is not an uncommon sight to see the flanks and 
hind quarters of cows literally plastered over with dried manure in a 
coat from one-quarter of an inch to an inch in depth. In such cases 
it is absolutely impossible to prevent contamination of the milk. 
Some of this filth will fall into the milk no matter how great precau- 
tions are taken. It is well to remember, as suggested by Pernot, that 
i.*ows which have access to stagnant water in summer almost invariably 
wade in the water to escape from flies and to cool themselves. The 
udders and teats thus become submerged in water which may be 
muddy and which may contain not only ordinary bacteria which 
cause fermentation and putrefaction, but also typhoid bacilli and occa- 
sionally other pathogenic bacteria. This filth after drying on the 
hair of the cows may be brushed off into the milk at milking time if 
the cows have not been previously groomed. 

Marshall has shown that even a comparatively clean hair from a 
cow may have on its surface from 50 to 3000 bacteria. Hairs covered 
with filth will obviously carry a much higher number of micro-organ- 
isms. The objection to hair in milk is therefore not due merely to 
the presence of the hair itself as a foreign body but to the fact that 
such large numbers of bacteria are transferred to the milk in contact 
with the hair. In view of this fact it is apparent that special precau- 
tion should be taken to groom the cows so as to remove the loose hair 
as fully as possible, particularly during the season when the coat is 
being shed. 

Methods of Milking. 

Dairymen have given much attention to rational methods of feeding 
cows and the sanitation of cows in stables but until recently little 
heed has been given to the matter of milking. This operation, how- 
ever, is as important as any other connected with the business of dairy- 
ing. It has long been known that some milkers are more efficient 
than others in that they secure a larger quantity of milk at each 
milking or succeed in maintaining the milk flow more uniformly and 
for a longer time. From the view-point of securing an adequate and 
sanitary milk supply the methods of milking are worthy of considera- 
tion for the reasons that it may thus be possible to secure more milk 
and milk of a better quality. 



121 

The variation in the work done by different milkers lies largely in 
the amount of attention which they give to the final process in milking. 
Some men are able to strip the cows cleaner. This has led to a 
number of practical tests for the purpose of determining the difference 
in the amount of milk obtained by a thorough stripping or removal 
of the residual milk. It is commonly considered that the average 
milker can obtain all the milk, or at least milk the cows sufficiently 
clean for practical purposes, merely by the ordinary process of strip- 
ping. In 1900, however, a method of milking was originated and 
recommended by a Danish dairy school teacher, Dr. J. Hegelund, and 
is designed to remove the residual milk more completely than any 
other known method of hand milking. The introduction of this 
method into the United States is largely due to the efforts of Pro- 
fessor F. W. Woll, of the Wisconsin Experiment Station. 

The Hegelund method of milking consists in a series of manipula- 
tions of the udder, which are carried out by the milker as soon as the 
main flow of milk has stopped. The manipulations as described by 
Professor Woll are essentially as follows : 

In the first manipulation the right quarters of the udder are 
pressed against each other, the left hand on the hind quarter and the 
right hand on the fore quarter, the thumbs being pressed on the out- 
side of the udder and the forefingers in the division between the two 
halves of the udder. If the udder is unusually large one quarter is 
taken at a time. The hands are pressed towards each other and at 
the same time lifted upward, this pressure and lifting being repeated 
three times. The milk thus collected in the milk cistern is then milked 
out and manipulation repeated until no more milk can be obtained in 
this way. The left quarters are then treated in the same manner. 

In the second manipulation the parts of the udder are pressed to- 
gether from the side. In this operation the fore quarters are milked 
one at a time by placing one hand with the fingers spread on the 
outside of the quarter and the other hand in the division between 
the right and left quarters. The hands are then pressed toward each 
other and the teat milked. When no more milk is obtained the hind 
quarters are treated in the same way. 

In the third manipulation the fore teats are grasped in the partly 
closed hands and pushed upward at the same time, the milk being 
drawn after each three movements. As soon as the fore teats are 
emptied the hind teats are milked in the same way. 

This method has been carefully tested by a number of dairy experts 
and commercial dairymen. At the Cornell Experiment Station Wing 
carried out a set of experiments to determine the value of the method. 
The cows were milked in the usual way by the regular milkers. As 
soon as a milker had finished a cow she was again milked by the 
Hegelund method. The amount of milk thus obtained was weighed 
and the percentage of fat determined by test. The milkers in this 
case were instructed to take no unusual pains in milking the cows in 



122 

order that the test might be a fair one. In the first experiment it 
was found that the residual milk obtained by the Ilegelund method 
was not detrimental to the production at the regular milking; or 
expressed in other words the milk was all gain. The amount of milk 
secured from each cow weekly by after-milking by the Ilegelund 
method varied from 3.75 to 13.5 pounds and the amount of milk fat 
from .5 to one pound, the average gain per cow per week being 8.75 
lbs. of milk and .6 lbs. of fat. In a second test of the Ilegelund method 
by Wing, the average gain in milk for each cow weekly was 1.9 lbs. 
and .55 lb. of milk fat. When the method was applied to the herd 
of a neighboring farmer containing nine cows the daily profit from 
the use of the Ilegelund method at the usual price of butter was 38c. 
These experiments indicate that there is a considerable financial loss 
in many dairies as a result of careless milking and that the milk thus 
left in the udder is lost. It appears to' be desirable from every stand- 
point to secure all the milk secreted by the cow at each milking. This 
requires but very little extra time and it is probable that clean milking 
has a tendency to increase the production. 

A thorough test of the Ilegelund methol was carried out by Pro- 
fessor Woll with cows in the herd belon^ine; to the Universitv of 
Wisconsin and in twelve commercial dairies. This elaborate series 
of experiments gave reliable data, not only on the value of the Hege- 
lund method but on the character of work done by different milkers. 
According to Woll the average daily poduction of milk was increased 
4.5% and the fat 9.2%. In a test of the Ilegelund method which was 
continued for four weeks the average daily gain per cow was one 
pound of milk. 

A similar average increase in milk yield was obtained for the 
twelve commercial herds in which the Ilegelund method was tested, 
the milk yield being incheased 1.08 lbs. and the fat .1 lb. per cow 
daily. The experiments as a whole were continued over a period of 
four months with cows in all different stages of lactation and indi- 
cated that the gain was a substantial one during all the stages. As 
estimated by Woll, if the fat production of each cow in Wisconsin be 
increased by .1 lb. per day it would mean an annual increase of 30,- 
000,000 lbs., it being assumed that cows give milk for 300 days in 
the year. In these tests the greatest amount of milk obtained by the 
Ilegelund manipulations after the regular milking had been done was 
5.5 lbs. per day. Naturally the greatest gain from the application of 
the Ilegelund method was shown in herds which were carelessly 
milked, but even after careful milking the manipulations yielded 
nearly a pound of milk per cow. 

It should be remembered that the milk obtained by the Ilegelund 
manipulations is very similar in composition to that of strippings. In 
Woll's experiments the milk thus secured contained 10.3% fat, being 
about two and a half times richer than ordinary milk. The highest 
percent of fat observed in the after-milking was 23. 



123 

A careful computation of the increased amount of milk due to 
careful milking indicated that some milkers may be worth as much 
as $10 per month more to the dairyman than other milkers, merely 
on account of the greater amount of milk obtained. 

From a sanitary standpoint there are no objections to the Hege- 
Jund method. In fact it has the considerable advantage that bacterial 
infection of the udder is greatly reduced as a result of the more 
complete removal of the milk. It is well known that the foremilk 
obtained at the beginning of milking is relatively rich in bacteria 
and this means simply that the milk left in the milk cisterns from 
the previous milking has served as a culture medium for the growth 
of bacteria. 

Milking machines. — The rapid strides made in modern dairying 
are to a large extent due to the invention and successful use of effect- 
ive machinery. The rapid increase in the size of our large cities 
and the increased demand for milk have caused a great development 
of the dairy industry and this in turn has brought about an increased 
demand for milkers. Recently the difficulty of obtaining farm labor 
of all kinds has been increasing and this is particularly true of milk- 
ing, which is considered one of the most unpleasant tasks on the 
farm. The work is very exacting and confining. It must be done at 
regular hours and there is no escape for holidays or vacation. Re- 
cently, therefore, many inventors have turned their attention and 
energy in the direction of perfecting milking machines in order to 
relieve the stress into which dairymen have fallen. 

According to the investigations of Professor Erf at the Kansas 
Experiment Station, inventors were working on milking machines 
as early as 1819, but it was not until 1878 that a really practical 
machine was devised. There are three principles upon which mechan- 
ical milking devices are based. The first apparatus was a milking 
tube, which provides an opening into the milk cistern and allows the 
milk to flow out. A great variety of these tubes have been devised 
and in some instances even such a simple device as a straw has been 
used. The great danger from the use of milk tubes, is that infection 
may be carried into the udder if the instrument is not strictly steri- 
lized before using. 

In a second group of milking machines pressure is applied at the 
base of the teat next to the udder. The operation of machines con- 
structed on this principal is essentially the same as that observed in 
hand milking. 

The third principal utilized in milking machines is suction. Cups 
from the air is exhausted, thus producing a vacuum, are placed 
over the teats. The pressure of the air on the udder thus forces the 
milk out into the vacuum chamber. This principle is essentially the 
same as that utilized by the calf in sucking. In fact considerable 
energy has been expended in trying to imitate as nearly as possible 
the action of the calf's mouth, in the operation of these machines. 



124 

At least five well known milk tubes, 25 pressure machines and 42 
suction machines have been invented and put into use in the United 
States. According to Erf, the Kansas Experiment Station has had 
in successful operation the Burrell and the Globe machines, the former 
having been used more extensively. In the various suction machines 
the vacuum is produced either by a vacuum pump, a steam jet air 
exhauster, or a water vacuum pump. On most' farms the mechan- 
ically operated vacuum pump is most practical. Boilers are ofter 
in use on dairy farms and a steam jet air exhauster is simple and 
efficient. The chief objection to this device as urged by Erf is that 
there may be irregularity in milking if the operator should allow 
the steam pressure to go down. The water pump vacuum cannot 
be used except where there is an abundance of water at high pressure. 
For running a vacuum pump system electricity or gasolene may be 
used as a motive power or denatured alcohol if that product should 
become sufficiently cheap. In Erf's experiments it appeared that 
the power required to operate the vacuum pump may be estimated 
at the rate of one horse power for each cow in small dairies, but the 
power required is relatively much less in large herds. The piping of 
the vacuum system is preferably conducted along the top of the 
stanchions. Professor Erf recommends that the stall pipes should 
not be less than one inch in diameter and that the pipe leading from 
the stall pipe to the vacuum pump should be at least l 1 /^ in. in 
diameter. If the Globe machine is used a compression pipe is also 
necessary in connection with the vacuum pipe. This arrangement is 
added to interrupt the suction and produce pulsations resembling 
the sucking movements of the calf. A safety valve is to be attached to 
the system to prevent too great negative pressure from the vacuum 

As has been well said by Erf and others, the practical value of a 
milking machine depends upon the reduction in the cost of labor, the 
elimination of hand milking, the maintenance of the quantity and 
quality of the milk, clean milking with adaptability of the machine 
to the average cow, reliability and securing returns corresponding to 
the capital invested. In Erf's experiments the saving of labor under 
average conditions was estimated to be from 30 to 40%. This allows 
file dairyman to hire fewer but more efficient laborers. In a compar- 
ison of hand milking and machine milking it appeared that on an 
average about one pound of milk per minute was drawn by hand, 
the average number of strokes being 106 per minute and the average 
time for the milking of each cow nine miutes. With the use of 
machines 2.4 lbs. of milk were drawn per minute and the average 
time required for each cow was seven minutes. But it should be 
remembered, however, that a single machine may be attached to two 
or more cows at the same time. In experiments along this line by 
Lane, there was a daily saving of 3.5 minutes per cow through the 
use of the machine. The number of pulsations in the vacuum system 



125 

may be 150 or more per minute, which is considerably in excess of 
the number of movements by the ordinary milker. 

The use of the milking machine relieves the workman of the objec- 
tionable part of hand milking. The necessary movements of hand 
milking are tiresome and the work itself is disagreeable at all times 
and particularly so in exceedingly warm or cold weather. 

In Erf's experiments with milking machines the quantity of milk 
was somewhat reduced from their use in the case of some cows, while 
in others it was increased. The quality of the milk was practically 
the same whether obtained by hand milking or by machines. In 
Lane's test there was a slight difference in the amount of milk in 
favor of the machines. It was found, however, that where milking 
machines were used carelessly they are a disadvantage to the dairy- 
man from the standpoint of milk yield, and actual loss in the quantity 
of milk may be suffered if the machines are not carefully manipulated. 

In Kansas experiments it appeared that the average cow milked 
somewhat cleaner by machine than by the average milker. 

With regard to the cleanliness of the milk obtained by the use of 
machines as compared with that secured by hand milking, there was 
a slight difference in Erf's experiments in favor of the machines, 
the number of bacteria in the machine-drawn milk being somewhat 
less. It is urged, however, that great care be taken to wash the teats 
of the cow thoroughly before the milking cups are attached, otherwise 
the suction and pulsating movements will dray large quantities of 
dirt and bacteria into the milk. Particular attention must be given to 
cleaning the machines after they have been used. This must be done 
before the milk has dried on the cups and tubes. It is commonly 
recommended that the machine, while connected together as for milk- 
ing should be operated to suck cold water and afterward warm water, 
thus rinsing all of the tubing. This should be followed with hot water 
containing sal soda or caustic soda. All parts of the pulsator must be 
washed with a brush and rinsed in boiling water, after which it is set 
aside to dry. As an antiseptic for cleansing the parts of the milking 
machine boracic acid has been found expensive and ineffective but 
has the one advantage that it preserves tin. Formaldehyde appears 
to be the most effective but lime is cheapest and perhaps most practical 
on a large scale. 

The careful bacteriological studies made by Stocking in determin- 
ing the sanitary relations of the milking machine indicate that unless 
care is used in cleaning the machines decomposing milk and bacteria 
accumulate in the rubber tubes and contaminate the milk as it passes 
through. Stocking is of the opinion as the result of his observations 
that the majority of the dairymen who* are now using machines are 
not taking sufficient precaution in sterilizing these machines. Their 
milk is therefore of poorer quality from a sanitary standpoint than 
that drawn by hand. If, on the other hand, the milking machine is 
kept in a sanitary condition, machine-drawn milk contains much 



126 

smaller numbers of bacteria than hand-drawn milk. In the experi- 
ments under discussion the number and percentage of liquifying bac- 
teria were considerably reduced by the use of machines and the 
keeping quality of the milk was increased. The use of cold water 
followed by hot water containing sal soda is not sufficient to prevent 
the multiplication of bacteria in milking machines. The same may 
be said for merely scalding by pumping boiling water thorn gh the 
machines and for subjecting the machines to steam without pressure 
for a period of thirty minutes. In Stocking's experiments where the 
rubber parts were placed in brine for several hours, after being washed 
or boiled in water containing powdered borax, a satisfactory sterili- 
zation was brought about, and the bacterial content of the milk was 
reduced. These tests indicate clearly that with careless management 
milking machines lower the quality of the milk but that when ma- 
chines are carefully managed and sterilized the quality is improved. 

Erf found in the use of milking machines that if the vacuum is 
normal and the cups fit the teats well the process of milking seems to 
annoy the cows less than hand milking. Some cows which cannot be 
milked by hand can be easily milked by machines. In the reports 
received by Lane from 11 dairymen it appeared that the effect of the 
machines upon the teats and udders was in no way objectionable and 
that the effect upon nervous, kicking and hard-milking cows was very 
favorable. Rarely the operation of the milking machines seems to 
annoy the cow. As a rule, however, it appears that the hard-milking 
cow is more easily managed by machine than by hand. The machine 
also seems to be especially adapted to heifers. 

The financial considerations in connection with the purchase and 
operation of a milking machine will depend partly upon the number 
of cows in the herd. According to calculations made- by Lane, the 
total cost of an engine or other power, a vacuum pump, vacuum tank, 
pipe and four milking machines for a herd of forty cows is about 
$516, or from $8.50 to $13 per cow, depending upon the size of the 
herd. Erf is of the opinion that in the small dairy the investment 
in a complete milking outfit would scarcely be justified. 

It has been found that the continued use of milk tubes has a bad 
effect upon the milk flow. The yield is diminished to such an extent 
that their use cannot be recommended. This result which has been 
frequently observed in addition to the danger of infecting the udder 
by using milk tubes should be sufficient to condemn them for ordinary 
purposes. As already indicated, however, milking machines have 
not proved to be objectionable from this standpoint. The cows appar- 
ently yield no less at any given milking than when milked by hand and 
the milk flow is maintained by the use of the machine with a total 
milk yield during the whole period of lactation as great as could be 
obtained by hand. The use of machines, however, is still somewhat 
in an experimental stage and has not been adopted on a scale which 
renders them of much importance in the dairy industry. 



127 

Rejecting the Foremilk. 

Dairymen who put forth a special effort to produce clean milk 
with a low bacterial content make a practice of discarding a few of 
the first streams of milk or the foremilk as it is commonly known. 
Numerous experiments by dairy bacteriologists have shown that the 
first few streams of milk contain a much larger number of bacteria 
than the rest of the milk obtained at each milking. In order to get 
rid of these bacteria it is not necessary to discard more than about 
four streams from each teat. A careful series of experiments have 
been carried out by Stocking to' determine the significance of rejecting 
the foremilk in the problem of reducing the total number of bacteria 
in the milk. The first two streams of milk from each quarter of the 
udder were found in every case to contain decidedly more bacteria 
tii an the fifth and sixth stream of any of the milk subsequently ob- 
tained. After ten streams had been removed from each teat the 
germ content of the milk did not vary greatly during the rest of the 
milking. From these experiments it would appear desirable to discard 
about six streams of milk from each quarter of the udder before saving 
the milk for use. 

As suggested by Stocking it might be supposed that' while the first 
few streams of milk contain large number of bacteria, the total num- 
ber of bacteria in the milk would not be greatly influenced when all 
the milk w T as mixed together. A test of this matter under carefully 
controlled conditions showed an average of 522 bacteria per c.c. 
when the foremilk was not rejected and 499 when the foremilk was 
not added to the rest of the milk. In this case the bacterial content 
of the milk was very low, whether the foremilk was rejected or not, 
the relative cleanliness of the milk being due to the sanitary precau- 
tions observed. The rejection of the foremilk, however, showed a 
distinct advantage in the reduction of the number of bacteria. 

It has already been suggested that there are at least three reasons 
why cows should be thoroughly milked at each milking. Careful 
stripping or the adoption of the Hegelund method of milking insures 
a larger yield at each milking and maintains the milk flow at a 
higher point. From a sanitary viewpoint it is also desirable to 
remove the milk from the udder as completely as possible at each 
milking. Any milk which may be left in the milk cistern at the base 
of the teat is subjected to infection with bacteria which make their 
way through the milk canal. If these be ordinary milk bacteria no 
harmful infection of the udder will result but they may multiply to 
a great extent during the twelve hours which elapse before the next 
milking and this is the explanation of the high bacterial content in 
the foremilk, for the foremilk is for the most part the milk which was 
left in the milk cistern at a previous milking. 

In experiments carried out by Stocking and others it was found 
that in the majority of cases the bacterial content of the milk was 
considerably higher when some of the strippings had been left in 



128 

the udder at the previous milking. In many cases the difference was 
very marked. Rarely, for some reason not easily understood, the 
germ content was higher in the cows which had been thoroughly 
milked. This must mean, however, that these cows had been subjected 
to greater chances of infection with milk bacteria than the other cows 
Aviiich had not been stripped. While the udder of the cow may be 
kept relatively free from milk bacteria by careful and thorough milk- 
ing and by furnishing the best practical sanitary conditions for the 
cows, it must be remembered that no amount of effort in this direction 
c*an keep the udder germ fee. It is therefore necessary to reject a 
few of the first streams at each milking. A part of the significance 
of the Hegelund method, in this connection, lies in the fact that the 
thorough manipulation of the udder in this process serves to dislodge 
some of the bacteria in the milk ducts and prevent the inevitable 
multiplication which would take place in these organisms if they 
were left in the udder until the next milking. 

Russell obtained some very suggestive results from experiments 
along this line. In one experiment the number of bacteria per c.c. 
gradually diminished from 6500 in the foremilk to 5 in the strippings 
and in another from 8100 to 10. These figures refer merely to 
ordinary milk bacteria which are not pathogenic for either man or 
the cows. The importance of thorough stripping becomes still more 
apparent, however, when it is remembered that pathogenic bacteria 
might easily gain entrance to the teats and there find opportunity for 
enormous multiplication if the strippings were not thoroughly removed. 
The matter is of greatest importance in stables which are not of the 
most sanitary construction or where cows are subjected to an excessive 
infection with bacteria which may be found in the manure and filth 
of the stables. If an outbreak of contagious mammitis or garget 
should take place in the stable a thorough stripping of the cows at 
each milking would become even more imperative in order to prevent 
the undue spread of this disease. 

The Use of Covered Pails. 

Neariy all pails used for milking purposes are larger at the top 
than at the bottom and in order that the size may be sufficient to hold 
all of the milk of any cow the diameter at the top must therefore be 
relatively large. This gives a large surface for the reception of 
bacteria which may fall from the udder or flanks of the cow, or 
which may gain entrance from the atmosphere of the stable. In 
order to reduce the surface over which bacteria may enter the milk 
of the pail, a large number of pails have been patented in which 
much of the top is covered over in order to reduce the open 
surface as much as practicable. There is obviously a practical limit 
to the reduction of the opening in the top of the pail for the reception 
of milk, but within this limit covered pails have been found to serve 
reasonably well the purpose for which they were devised. 



129 

Numerous comparative tests have been made of such pails, one of 
the most extensive being that of Stocking at the Store's Experiment 
Station. This investigator made two sets of parallel tests: in one 
case milk drawn into an ordinary open pail was compared with milk 
drawn into a covered pail devised for excluding dirt; and in the 
other case milk drawn into an open pail was compared with that 
strained immediately after milking. When the milk was examined 
for the presence of dirt it was found that the milk in covered pails 
contained only 37% of that in open pails, while the amount of dirt 
in strained milk was more than half as much as was found in un- 
strained milk. It is apparent therefore that the covered pail excluded 
63% of the dirt, while the strainer removed less than half. 

Furthermore in these experiments the covered pail was found to 
exclude 29% of the total bacterial content and 41% of the acid- 
producmg bacteria, while by straining milk only 11% of the total 
number of bacteria was removed. 

It is of even more importance to note the effect of covered pails 
upon the number of bacteria in the milk after it has been allowed to 
stand for a reasonable length of time. In Stocking's test after milk 
had stood fifty hours at a temperature of 70 degrees F., samples 
from the covered pail contained a smaller number of total bacteria 
and always contained fewer acid-producing bacteria. On the other 
hand in strained milk the total number of bacteria and the number 
of acid-producing bacteria, was higher than in milk which had not 
been strained. Samples of milk from covered pails as a rule curdled 
somew T hat sooner than similar samples from open pails and the same 
was true of strained milk. 

While it may not be an easy matter to explain why the keeping 
properties of milk are not always improved by the use of covered 
pails, it should be remembered that in the above-mentioned tests the 
milk was kept considerably longer than is the case in ordinary house- 
holds and at a temperature above that which the housewife uses for 
preserving milk. As urged by Stocking, the demand of the milk- 
consuming public is not for milk which can be kept indefinitely but 
for milk which may be used with reasonable promptness by children 
and adults without danger to health. In this respect the use of 
covered pails accomplishes all that could be expected of them. As 
compared with straining the results are all in favor of the covered 
pail. This matter will be referred to further in the next section. 

Straining, Filtering, Purifying, Aerating and Cooling Milk. 

Nearly all dairymen strain the milk as soon as it has been drawn 
and this practice is almost universally recommended in publications 
relating to the care of milk. Milk drawn under ordinary conditions 
which prevail on the average dairy farm becomes contaminated to a 
greater or less extent with dirt, dust, hair and other foreign bodies 
which invariably carry bacteria. Straining has therefore always been 



130 

recognized and recommended as a practical means of removing this 
filth. Too much reliance, however, should not be placed upon strain- 
ing, since as already indicated and as will be discussed further strain- 
ing mav not reduce the number of bacteria in the milk. 

A large variety of strainers have been placed upon the market and 
are in common use. In some cases the milk pail is furnished with 
a partial cover on one side, in the center of which there is a wire 
strainer with fine mesh. When such pails are used for milking the 
milk is allowed to run through the strainer immediately after it is 
drawn. This is perhaps the least satisfactory of all forms of strainers. 
The meshes cannot be made fine enough to remove. the minute particles 
of dirt and unless the strainer is cleaned after each cow is milked and 
before the milk has been poured through it some hair and other dirt 
which will have fallen on the top of the strainer will be washed into 
the milk. 

In other cases similar wire-mesh strainers are placed over the tops 
of cans or other receptacles into which the milk is poured in the milk 
room. These have the one advantage that the strainer is not subjected 
to pollution with hair and filth from the outside. 

It has long been known that even strainers with the finest possible 
mesh will allow some filth to pass through. The attempt has there- 
fore been made to reduce the quantity of dirt which passes through 
to a minimum. In order to secure this several thicknesses of fine 
cloth have been used of cotton or woolen texture, preferably the latter. 
Some dairymen have made use of a strainer consisting of a layer of 
cotton batting with a layer of fine cloth above and below. 

It should be understood at the outset that bacteria are much smaller 
than the fat globules in milk and strainers therefore cannot have the 
least effect in reducing the bacterial content of milk. In fact if 
cloth, cotton batting or wire strainers are not thoroughly cleansed at 
frequent intervals bacteria will multiply in the milk particles which 
adhere to such strainers and will be washed into the milk receptacle 
with the stream of milk. The number of bacteria in the milk will 
thus be increased rather than diminished. 

Marshall has called attention very pertinently to the fact that alto- 
gether too much energy is expended upon the straining of milk. 
Cheesecloth has a comparatively loose texture and it is obviously im- 
possible by the use of a sieve with a one-fortieth inch mesh to inter- 
cept bacteria which are one-ten-thousandth of an inch or smaller in 
diameter. Conn, Marshall and many other dairy investigators have 
called attention to the fact that all soluble filth will be dissolved and 
washed through the strainer however small the meshes may be. If, 
for example, comparatively large particles of manure or other soluble 
filth should be caught by the. strainer at first, these particles will soon 
be dissolved by the stream of milk and washed on through the strainer. 
Moreover in this process nearly all of the bacteria which may be 
attached to hair, straw or other insoluble particles of foreign matter 
will likewise be dislodged and washed into the milk. 



131 

In the exhaustive experiments of Conn it has been clearly shown 
that the number of bacteria is the same in strained and unstrained 
milk. Straining therefore as ordinarily practiced merely removes 
the visible particles of filth, while all of the soluble manure or other 
dirt readily passes through the strainer. The dairyman is practically 
under the necessity of straining milk, since his customers would 
strenuously object to the presence of hair or other visible particles 
of filth in the milk. Nevertheless, dairymen understand that even 
alter milk is strained the amount of filth really present in the milk 
is essentially the same as before and the milk inspector will find by 
a bacteriological test that the germ content has not been affected. 

It is desirable to strain the milk in all cases, but if it were drawn 
with sufficient care straining would not be necessary. It is obviously 
far better and more sanitary to prevent filth and bacteria from gain- 
ing entrance to the milk than to attempt to remove this material later 
by the device of straining. Moreover in order to prevent the use of 
strainers from becoming a positive disadvantage it is quite necessary 
that the strainers should be frequently cleansed with boiling water, 
steam or by some other antiseptic method and for this purpose it is 
best to have several strainers for use during each milking. 

A number of filters have been devised for purifying milk. These 
have been constructed of paper, cellulose, gravel, sand, porcelain and 
other materials. The filters used for this purpose are operated on 
essentially the same plan as in filtering water to bring about a reason- 
able purification. Milk filters are scarcely practicable in a small 
dairy for the reason that they are somewhat expensive and require 
too much time for operation and for properly cleaning them. In the 
case of milk dealers who handle a large quantity of milk it may be 
desirable to establish a sand filter, in which the milk is forced upward 
through a deep layer of sand. After each filtering process the sand 
must be removed, cleansed, baked and dried. Such sand filters insure 
the removal of filth somewhat more effectively than the ordinary 
strainer but do not greatly reduce the bacterial content of the milk. 
A filter of this sort used in Norway was found to be much more 
effective than an ordinary strainer. 

Tn considering the problem of purifying milk after it has been 
drawn it should be remembered that the germ content of such milk 
is practically proportional to the amount of dirt. As shown by Back- 
haus about one-half of the fresh cow dung which falls into milk dis- 
solves so that it cannot be estimated by any common method for the 
determination of the amount of dirt. For such determination it is 
sometimes recommended that the milk be allowed to settle and be 
filtered through glass wool. 

Since sieves, strainers and filters are not found satisfactory in 
cleaning milk, resort has been had to purification of milk by means of 
the separator. From a mechanical and bacteriological standpoint this 
is quite satisfactory. Nearly all of the dirt and bacteria in milk have 



132 

a higher specific gravity than the milk and are therefore removed in 
the centrifugal slime. Many experiments have shown that separator 
slime in the case of milk from tuberculous cows contains nearly all of 
the tubercle bacilli and is very dangerous for feeding to pigs without 
previous sterilization. It has been found possible to remove a large 
part of the dirt and most of the bacteria in milk by running all of it 
through a separator and later combining cream and milk. There are 
some disadvantages attached to this method, however. In the first 
place considerable labor is involved in the process of separation. Then 
it is claimed that after separation and subsequent mixing of the 
cream and milk, the cream does not rise as thoroughly and completely 
as in untreated milk and this matter led to suspicion in the minds of 
milk customers and to complaints about the fat content of the milk. 
Moreover where the method, of purification by separation has been 
adopted on a large scale in cities where the established milk standard 
sets a relatively low minimum of fat it is possible for milk dealers to 
separate all of the milk and remix with the skim milk only enough 
cream to bring the mixture up to the required standard. En some 
localities complaints to this effect have been made by the dairy farmers 
who feel that they are thus done an injustice and that the milk dealers 
are receiving an unearned profit. In some tests of purification of milk 
by separation evidence has been obtained that it is best to carry out 
this process after the milk has cooled. The fat separation may not 
be as complete in cold milk but this fact is of no significance since 
the fat is to be mixed again with the skim milk. 

It has long been believed and many experiments have appeared to 
indicate that there are considerable advantages in the prompt aeration 
of milk. As milk is ordinarily cooled by allowing it to trickle over 
the surface of corrugated metallic coolers aeration is accomplished at 
the same time as the cooling. These combined coolers and aerators are 
in wide use among progressive dairymen. In the United States 
some of the most extensive experiments to determine the effect of 
aeration upon the condition and bacterial content of milk have been 
carried out by Marshall at the Michigan Experiment Station. In the 
ordinary gas content of milk this investigator found that on an 
average 81.5% was. cprbon dioxide and 2.4% oxygen. Aeration re- 
duced the content of carbon dioxide 35% and oxygen 20%. The 
presence of carbon dioxide in milk was found to be of more benefit 
since when present in quantities exceeding 33% it appears to restrain 
or prevent the growth of bacteria. 

Marshall has well called attention to the fact that milk undergoes 
a process of aeration from the time it leaves the cow until it is con- 
sumed. This process is indicated by the diminution in the amount 
of carbon dioxide and the increase in the amount of oxygen. Any 
aerating method which increases the exposed surface of the milk 
facilitates aeration. It should be remembered that while the milk is 
exposed in thin layers for the purpose of aeration al undant oppor- 



133 

runity is offered for the absorption of disagreeable odors and unde- 
sirable gases unless the operation is carried, on in a pure atmosphere. 

As a result of his study of the aeration of milk Marshall recom- 
mends that it should be done before the milk loses its animal heat 
and that the milk should be made to flow slowly over an extensive 
surface. This investigator believes that aeration should be done 
immediately after milking and should precede cooling since in his 
experiments the most satisfactory results were not attained when 
aeration and cooling were carried on simultaneously. In certain 
English experiments it was found that the aeration of milk extended 
the time during which it remained sweet and also eliminated the 
animal odor. Moreover Barthel found that aeration retards fermen- 
tation to some extent. 

The general subject of the refrigeration of milk is discussed in 
Chapter VIII and in this connection it is merely necessary to make 
brief mention of the subject. As indicated in the chapter on refrig- 
eration milk bacilli multiply much more rapidly at high than at low 
temperatures. It is desirable therefore to reduce the temperature 
of the milk to 50° or 60°F. as soon as possible after milking. The 
temperature of 40° is still more effective, but only a comparatively 
small percentage of dairymen have facilities for cooling their milk 
down to this point. If the milk is to be delivered within a few hours 
after it is drawn the bacterial content will not have increased greatly. 
In fact during the first two or three hours it may actually diminish, 
if however morning milk is to be delivered at night or night milk in 
the morning it is necessary that cold should be applied in order to 
prevent the multiplication of bacteria and the premature souring 
of the milk. This may be accomplished as indicated in the chapter 
on refrigeration, by the use of spring water, other running water, 
ice or artificial refrigeration by means of machine. 

Cake of Dairy Utensils. 

It is of course quite unnecessary to present any argument to the 
progressive dairyman for the purpose of convincing him of the 
necessity of strict cleanliness in connection with all vessels and uten- 
sils with which milk comes in contact. The dairyman is already 
assured of the necessity for such care. Nevertheless, there are still 
in use on some dairy farms utensils and time honored methods of 
caring for them which cannot be approved by modern sanitarians, 
in all lines of modern industry connected with the manufacture of 
food products great progress has recently been made in devising 
apparatus and methods which minimize the amount of contact of 
human hands and other objects which might carry contamination to 
the food products in any stage of the manipulation connected with 
their preparation for the market. The same is true in the dairying 
industry. Not only must all dairy utensils be clean at the time of 
use but in order to satisfy practical demands they must be easily 



134 

cieansed. This point is of more importance than the mere general 
appreciation of the necessity for cleanliness, for if milk utensils are 
not easily cleaned and require too much labor to remove all particles 
of milk and other filth which may become attached to them it is 
merely a question of time when the labor of cleansing will appear 
too great and some carelessness will be permitted. 

Unclean dairy utensils are one of the important sources of con- 
tamination of milk. Any particles of milk or cream which remain 
attached to the utensils from a previous use serve as a medium for 
retaining and allowing the multiplication of milk bacteria, As soon 
therefore as fresh milk is placed in these utensils a portion of this 
partly dried milk is softened or again changed into a fluid form by 
the presence of the fresh milk and the bacteria which the filth contains 
are set free to operate in producing undesirable changes in the milk. 
The object of cleansing milk utensils is to remove the material in 
which bacteria may grow, and thus render the milk vessels sterile 
from a bacteriological standpoint. Millions of ordinary milk bacteria 
may be concealed in minute crevices or corners in sour or partly 
dried milk which has been allowed to remain in such places. 

On account of the great difficulty or practical impossibility of 
cleansing them, no wooden vessels of any sort should be used in hand- 
ling milk. The frequent washing to which they must be subjected 
and the partial drying between the periods of use sooner or later 
cause checks in all kinds of wooden utensils in which milk finds 
lodgement and from which it cannot be removed by any practical 
system of cleansing. Glass and earthenware vessels have been used 
as milk utensils and are very efficient for this purpose, answering all 
of the sanitary demands which could be made of such utensils. They 
are too expensive, however, and too easily broken, for practical use. 
Tinned metal answers most perfectly the practical and sanitary re- 
quirements of milk utensils. The tin however should be of good 
quality, heavy, and smoothly laid over the iron base of the utensils 
«o that the rougher metal is completely covered and so that no joints, 
crevices, seams or corners are left exposed. 

As has been urged by all dairy experts seemless utensils of pressed 
tin are greatly to be preferred. Milk pails should have no corners in 
which milk is left. Aerators, coolers, strainers and other utensils 
should also be smooth and with as few irregularities of surface as 
is consistent with their construction. The same rule should apply to 
dippers and delivery cans. Particular attention must be given to the 
cream separator after each using, for this instrument is one of the 
most complicated in use on dairy farms. 

Erf and others have conducted a number of experiments having in 
view the efficiency of methods of cleaning dairy utensils. For prac- 
tical purposes hot water or steam and alkali and a scrubbing brush 
or coarse cloth are the chief materials to be used in cleaning milk 
utensils. All vessels should be cleaned immediately after using and 



135 

before the milk has had opportunity to dry. Milk utensils should 
first be rinsed in lukewarm or cold water for the purpose of removing 
as much of the milk as possible. If boiling water or steam is applied 
at once the milk in contact with the utensils would be coagulated and 
wouid adhere much more firmly than would otherwise be the case. 
After rinsing in lukewarm water milk utensils should be thoroughly 
scrubbed with hot water to which a washing powder or caustic soda 
has been added. The addition of an alkali saponifies the fat of the 
milk and thus helps to remove it from the surface of the tin. Com- 
mon commercial soaps should not be used in washing milk vessels. 
After scrubbing with hot water and an alkali it is desirable to apply 
live steam. Steam is not always accessible in small dairies but 
since it is the cheapest and most effective means of destroying 
bacteria and finishing the cleansing process a steam boiler should be 
installed in all large dairies. 

Where steam is not to be had a five per cent solution of washing 
powder applied vigorously in hot water for about ten minutes will 
insure the proper cleansing of dairy utensils provided they are after- 
ward rinsed with hot water. A hot solution containing ten per cent 
of borax w T ill assist greatly in sterilizing milk utensils and also has 
the effect of helping to preserve the tin. This material, however, 
should be thoroughly rinsed off in order to avoid getting borax in the 
milk. 

The old-time practice of using wash rags and various kinds of 
cloths in cleansing dairy utensils is not very satisfactory. These rags 
cannot be sterilized without thorough boiling or dipping into an anti- 
septic solution followed by treatment with boiling water. These 
operations, however, are not usually carried out and the result is 
that the ordinary wash rag adds far more bacteria to the surface of 
milk utensils than it removes. If ordinary dish cloths are to be used 
for wiping dairy utensils they must be steamed or boiled in a washing 
solution after each using. Obviously the most satisfactory and 
sanitary method of cleansing the milk utensils is to remove all particles 
of filth and milk by means of a stiff brush, rinse the surface with 
hot water and then apply steam, after which the utensils are allowed 
to dry without being wiped or touched in any way. 

Detailed directions are furnished by the manufacturers of all milk 
separators regarding the cleansing of these machines. It is com- 
monly observed that these directions are followed literally at first, 
after which in some cases a slight laxity is allowed in methods of 
cleansing. It is unfortunately true that separators constitute one 
of the important sources of the bacterial contamination of milk. For 
the purpose of securing evidence of the importance of the thorough 
cleansing of separators, Erf compared the efficiency of simply flush- 
ing- out the bowl with water and of thoroughly washing the separator. 
Samples were then taken from milk run through the separators at 
the next using. In these experiments it became obvious that cream 



136 

separators must be thoroughly washed after using. For this purpose 
a brush and a five per cent solution of borax or some other washing 
powder is recommended. All parts of the machine are then to be 
rinsed in hot water or treated with steam and allowed to> dry while 
hot. It was found that wiping with an ordinary cloth added immense 
numbers of bacteria to the parts of the separator. The bacterial 
contamination of the milk was found to be increased three to five 
times by running it through a separator bowl which had merely been 
flushed and allowed to stand since the previous milking. If still 
greater negligence were permitted in the care of the separator the 
skim milk from the machine would bcome harmful even to the 
calves to which it is fed. 

Reference has already been made to the use of the centrifugal 
separator in removing filth and bacteria from milk. If the separator 
is properly cleansed after each using it brings about a striking reduc- 
tion in the number of bacteria in the milk. When properly cared 
for, therefore, a separator may be considered as a clarifier and a puri- 
fier of milk but when allowed to become contaminated it constitutes 
a fruitful source of bacteria which are passed on into the milk which 
runs through the machine. 

As an alkali for an addition to the washing water, sal soda is as 
convenient and satisfactory as any that can be used on the dairy farm. 
After the use of such a solution it is not necessary to dry milk uten- 
sils with cloth even if no steam is available, for if rinsed with boning 
water and inverted on a clean shelf placed so as to receive the direct 
rays of the sun the vessels will dry quickly and thoroughly. 

In the plan for the improvement of market milk as suggested by 
Pearson attention is called to a number of practical points which 
must be observed in the care of milk utensils in order to insure a 
pure milk supply. Among other things it is recommended that the 
joints and seams of metal utensils should be made smooth and all 
cracks filled with solder. No old, rusty or badly jammed milk 
vessels should be used for the reason that they are difficult or im- 
possible to clean. Milk utensils should not be used for any other 
material and none of the milk utensils except the milk pails should 
under any consideration be carried into the milking stable. Pearson 
also calls attention to the necessity of cleaning all these vessels imme- 
diately after using and this cleansing should include the surfaces and 
parts of every utensil. It is not enough to clean merely the inside, 
for contamination left on the outside of milk cans or pails may find 
its way into the milk in handling. When not in use all milk vessels 
should be kept inverted, without covers, in a clean, dry, dustless and 
odorless atmosphere. 

General Care of Milk. 

As soon as milk is drawn it should be strained through sterile cloth 
and absorbent cotton and removed from the stable to the milk room. 



137 

Before straining it may be quickly weighed if the dairyman desires 
to keep a record of the milk yield of each animal. After straining 
the milk should be run over a cooler, during which the temperature 
is reduced from body heat to about 40°. This operation occupies but 
a short time' and of necessity allows a satisfactory aeration of the 
milk. The subsequent care of the milk will of course depend on the 
use to which it is put and the method of handling adopted by each 
dairyman. It may be at once bottled and capped, after which it is 
placed in clean boxes and kept cool by water or ice until it is deliv- 
ered to customers. If milk is carried to customers in cans rather than 
in bottles the cooling process should still never be omitted except in 
case of small dairies in the immediate vicinity of consumers under 
conditions which permit of the delivery of the milk before it has 
lost its animal heat. Even in such cases it is better to cool the milk 
before transporting it and to deliver it to the consumer at a tempera- 
ture not above 60 F. for the apparent retention of the original animal 
heat is very deceptive, especially in summer and in warm climates. 
It is obvious that in the South, in the heated season, the milk may be 
kept approximately at animal heat by the high temperature of the 
atmosphere. It may therefore remain about at the body temperature 
until it sours. 

In all cases it is important from a bacteriological standpoint that 
milk be cooled to at least as low as 45 degrees F. within fifteen minutes 
after being drawn and that it be kept at as low a temperature as 
practicable from that time until its delivery to the consumer. While 
on the farm milk should be stored only in a regular milk room prop- 
erly protected against contamination with dust, filth, or odors, and 
kept in covered vessels. If milk is stored in a cold water tank the 
water must be changed frequently enough to prevent the development 
of bad odors in it. In order to get the best results from this system 
of cooling it is desirable to have the level of the water above that of 
the milk in the can. If ice boxes are used for cooling they should be 
thoroughly scrubbed at least once per week to prevent the development 
of molds and disagreeable odors. Under no consideration should ice 
be put into milk and milk should never be allowed to freeze in ordi- 
nary cans. It is also important from a bacteriological standpoint that 
night and morning milk should not be mixed. 

If milk is delivered to consumers in bottles the dairyman should 
take the precaution of scalding the bottles before each refilling. It 
is of course commonly supposed that milk bottles are properly cleaned 
at the house of the consumer before being returned to the dairy. 
Different people, however, have different ideas of what constitutes 
proper cleansing and considerable difference has been observed in 
the efficiency of this work. Moreover in carrying the bottles from 
the consumer back to the dairyman there is the opportunity for con- 
tamination with dust and bacteria. Especial precautions must be 
taken in the use of bottles returned from houses in which infectious 



138 

diseases prevail, for the slightest carelessness may permit the con- 
tamination of such bottles and this would mean the probable infec- 
tion of other individuals who might drink the milk from these bottles. 
These dangers are largely avoided by the use of paper milk bottles, 
which have lately come somewhat into vogue. Two or three types of 
paper milk bottles have been suggested, one stamped in a solid piece 
out of pulp paper, and another rolled spirally like a paper mailing 
tube. The form is cylindrical, being of the same size at either end. 
The surface of the paper is covered with paraffine to prevent, the milk 
from soaking through. These bottles in pint size cost about 40 cents 
per hundred or $3 per thousand. They are kept in a clean place 
before using and are to be used only once. They are of course much 
tighter than glass bottles and the trouble of collecting and washing are 
avoided. Paper bottles seem destined to come into more general use. 

Cure of milk kept on the farm. — Obviously the same care in gen- 
eral should be bestowed on milk which is kept on a dairy farm as 
upon that which is sold to customers. As should be obvious it is 
unnecessary to give any attention to perfectly fresh milk which is 
used at once for household purposes, but the milk which must be kept 
for the short period between milkings requires the usual attention to 
prevent it from souring prematurely or becoming contaminated. For 
the milk which is not to be kept longer than the period between two 
milkings a temperature of 60° is quite sufficient to prevent undue 
multiplication of bacteria. In fact as is shown in the chapter on the 
bacteriology of milk these micro-organisms do 1 not begin to increase 
in milk for a few hours after it has been drawn unless the tempera- 
ture of the milk is high and the amount of contamination unusually 
large. The souring of milk which takes place so soon in hot weather 
is not due to thunder storms or to other agencies than bacteria. The 
rapid souring of milk in warm weather is entirely due to the fact 
that relatively high temperatures are favorable to the development 
of bacteria. The micro-organisms which may gain entrance to milk, 
however, may cause other changes than souring. More or less rapid 
decomposition of the protein of the milk may be brought about and 
this leads to a very disagreeable change in the flavor and odor of the 
milk. In order to prevent these changes a temperature of 50° is 
desirable. In case of the occurrence of any infectious disease in the 
household of a dairy farmer strict precautions must be observed in 
preventing the patient or nurse from contaminating the milk which 
is used by other individuals, for if these precautions are not observed 
the milk may easilv become the agent for carrying the disease to 
other members of the household and thus prolonging the expense and 
annoyance of quarantine and treatment as well as offering greater 
opportunity for the infection of the milk which is sold to regular 
customers. 

The relationship between milk and digestive disturbances which 
may be produced in individuals who drink it is discussed in the 



139 

chapter on dietetics of milk, with special reference to infant feeding. 
Tn order to prevent the occurrence of digestive disturbances, especially 
in children, it is the common practice in the household to pasteurize 
or sterilize the milk even when it is believed to be reasonably health- 
ful and sanitary. As mentioned in the chapter on pasteurization all 
disease germs and most of the bacteria which cause fermentation in 
milk are killed by heating the milk to a temperature of 140 degrees 
F. or higher for a period of ten to thirty minutes. The higher the 
temperature the shorter the time required for pasteurization. There 
are certain disadvantages which attach to pasteurization and steriliza- 
tion of milk. If milk is boiled it acquires a cooked taste which 
renders it far less appetizing. Moreover its composition is consid- 
erably changed. Even pasteurization at temperatures too low to 
coagulate albumen produces some undesirable effects in milk. If the 
milk is not stirred during the process of pasteurization certain por- 
tions of it may be heated more highly than others and may thus 
acquire a cooked flavor. Moreover it must be remembered that in the 
process of pasteurization the lactic acid bacteria are destroyed. The 
elimination of these bacteria allow other still less desirable organisms, 
which produce decomposition of the protein, to multiply in the milk 
and render it far less suitable for food than it would be with the 
lactic acid bacteria present. Pasteurized milk if it is to be preserved 
for many hours after pasteurization must be kept .at a low tempera- 
ture in order to prevent the development of the bacteria which may not 
have been killed. 

It is apparent from the previous discussion that the best method 
for securing pure sanitary milk for household use is to prevent the 
contamination of milk with bacteria or filth from the time it leaves the 
udder until it is consumed. If this is done no treatment of the milk 
is necessary except to keep it at a low temperature. Where any 
doubt exists, however, regarding the possible bacteriological examina- 
tion of the milk it should be pasteurized at temperatures which will 
not give the cooked flavor and should then be kept at a temperature of 
50 degrees F. or lower. 

The same care mentioned as desirable in connection with milk 
intended for use in the household and on the dairy farm should pre- 
vail in the household of the consumer. It is undoubtedly true that 
the milkman is frequently held responsible for the premature souring 
of milk and for other unfavorable changes which are really due to 
carelessness in the handling of milk after the consumer has received 
it. It must be admitted that the consumer is responsible in this 
matter as well as the producer. Attention has frequently been called 
to the fact that however free the milk may be from bacteria and filth 
at the time when it is delivered, and however low the temperature of 
the milk, it will not long remain fit for human consumption unless it- 
is handled in the proper manner. As already indicated, the bacteria 
in milk do not begin to multiply rapidly until several hours after it 



140 

has been drawn. By the time the milk reaches the consumer the 
bacteria are therefore ordinarily in a condition to begin rapid multi- 
plication. This can be prevented only by keeping the milk at a low 
temperature until it is consumed. It is scarcely necessary to mention 
the fact that strict precaution should be observed in preventing the 
further contamination of milk in the household by dust or other filth 
or by the use of unclean utensils. 

The present wide-spread fear of infection and digestive disturb- 
ances from the consumption of milk can be removed only by the 
organized cooperation of progressive dairymen in educating the 
public to a better appreciation of the food value of pure milk. In 
this connection after the consumer has had some experience in hand- 
ling milk in the household according to modern sanitary requirements, 
he will the better appreciate the value of milk and will be more willing 
to pay a reasonable price for milk produced under sanitary conditions. 
The advance in the market price of milk in the average city during 
the past few years has not been as great as has taken place in almost 
all of our other food materials. Nevertheless the cost of milk pro- 
duction has increased greatly. This is due to the increased wages 
paid to farm labor, the greater value of cows, the increased price of 
land and the greater amount of labor necessary to produce, handle 
and deliver milk according to the requirements of the municipal 
boards of health. The public may therefore be reasonably expected 
to show a willingness to pay an increased price for milk which is 
known to be produced and handled under cleanly and sanitary 
conditions. 



141 



CHAPTER VII. 

TRANSPORTATION AND SALE. 

The condition in which milk reaches the consumer depends almost 
as much upon the care used, in transportation as on the attention 
which it receives at the point of production. In small towns the 
problems of transportation are very simple. The producing farm 
.is distant but a few miles at most from the consumer, and the milk 
is transported in wagons or carried by hand from house to house. 
In some tropical countries the problem is still further simplified by 
driving the cow or goat along the street and milking out the required 
amount before the door of the consumer. In country towns the milk 
is delivered so promptly after milking that it frequently still retains 
its animal heat when it reaches the consumer. At any rate it is 
delivered twice per day, and therefore the matter of cooling may be 
left entirely to the individual householder. 

With the rapid development of our large cities the transportation 
of milk has presented problems which have exercised the ingenuity 
of producers, dealers and sanitarians alike. It requires 900,000 
gallons of milk and cream daily to supply our 15 largest cities. In 
former years a much larger percentage of the milk was produced in 
the immediate vicinity or even within the limits of these cities. 
Recently, however, land values in such locations have become too 
high for profitable dairying, and as a result the milk has been trans- 
ported from greater distances. The actual distance of the milk 
supply from our large cities varies from a few to nearly 400 miles. 

This means a transportation period of twelve hours or more by 
railroad in addition to the time required for the distribution of the 
milk after it reaches the terminus in the city. Even if the best of 
attention were bestowed upon the milk at the producing farm it 
could not be kept sweet during a trip of 400 miles in an ordinary 
baggage car without refrigeration. The obvious problems in this 
connection have been met in different ways in different cities and 
will be discussed in the following paragraphs. 

Milk is transported to large cities by steam railroads, electric rail- 
roads, steam vessels or by wagon. The percentage carried by these 
different means varies in different cities but on the whole steam roads 
carry the greater part of the milk. St. Louis, Cincinnati, New Or- 
leans and Milwaukee are notable exceptions to this statement. In 
the case of these cities more than half of the milk produced is so near 
as to be delivered by wagon, in fact in New Orleans nearly all of it 
is so carried. Electric railroads carry large quantities of milk to 
cities, particularly Philadelphia, Cleveland, Detroit and Washington. 



142 

New York and San Francisco receive some of their milk supply by 

steamboat. The following table prepared by Ward shows the relative 

percentage of milk carried to cities by steam railroad (including 
electric railroad) and wagon: 

Carried by steam Carried by 

Cities — • railroads — wagon — 

Percent Percent 

New York 88 12 

Chicago 97 3 

Philadelphia 90 10 

St. Louis 43 57 

Boston 80 20 

Baltimore 78 22 

Cleveland 84 16 

Buffalo 85 15 

San Francisco 55 45 

Cincinnati 25 75 

Pittsburg 90 10 

New Orleans 14 86 

Detroit 50 50 

Milwaukee 25 75 

Washington 57 43 

In estimating the per capita consumption of milk in different 
cities a number of factors enter into the computation and the figures 
usually given are at best only approximately correct. As estimated 
by Ward for 1900 the per capita consumption in pints per day was 
a,s follows: New York .66, Chicago .75, Philadelphia .46, St. Louis 
.41, Boston 1.17, Baltimore .39, Cleveland .48, Buffalo .70, San 
Francisco .63, Cincinnati .61, Pittsburg .74, New Orleans .27, De- 
troit .70, Milwaukee .69, Washington .34. This represents not only 
the actual individual consumption but also the amount used in the 
manufacture of butter, cheese, ice cream, condensed milk, and oleo- 
margarine. 

In supplying milk to large cities one of the points which must first 
be settled is the rate of transportation charge. This varies greatly in 
the region of different cities and in some cases varies on different 
roads running to the same city. Such conditions have led to endless 
controversies between the dairy farmers, the railroads and the milk 
dealer. The rate charged for the transportation of cream varies from 
5 to 10 cents more per can to twice the usual rate for milk. There is no 
uniformity in the matter. The only explanation offered by the rail- 
roads for charging a higher rate for cream is that the rate is based on 
the value of the product, not on the difficulty of transportation. 

Milk Supply of New York City. 

New York City consumes daily about 1,500,000 quarts of milk 
and cream. This is supplied by 200,000 cows and comes from dis- 



143 

tances varying from a few to 400 miles. It is estimated that 87 per 
cent of this supply comes from the State of New York and the bal- 
ance from Pennsylvania, New Jersey, Connecticut and Massachu- 
setts. There are about 550 milk shipping stations in the State 
engaged in forwarding milk to Greater New York. 

According to Whitaker most of the milk sold in New York City 
is under the control of a few concerns which own the shipping sta- 
tions in the country districts and are receivers, wholesalers and re- 
tailers at the same time. The number of stations owned by different 
corporations varies from one to 27, and ten concerns control one 
quarter of the whole number. The small dealer is gradually being 
put out of business and at present 90 per cent of the milk is handled 
by 125 dealers. Some of these dealers issue very stringent orders 
to the farmers from whom they buy milk. In one case at least it 
is required that the cows be healthy, the barns well ventilated, milk 
cooled to 38 °F. immediately after drawing, no turnips, brewery or 
distillery grains, linseed meal or silage to be fed, milk room to be 
separate from the stable and night's and morning's milk to be kept 
separate. 

In New York the shipping station is called a creamery and the size 
of the cans is 40 quarts. The farmers live for the most part within 
a radius of twelve miles from the milk station. Most of the dairy 
herds number 20 to 100 cows. The night's milk is supposed to be at 
a temperature not above 60 °F. when delivered at the station in the 
morning. The milk is delivered at the station by 9 a. m., all sorts 
of wagons being used for this purpose. As a rule no attempt is made 
to furnish refrigeration for the milk on the way from the farm to 
the station. A canvas may be thrown over the cans in hot weather 
to protect them from the sun. If the farmers live ten or twelve miles 
from the station collectors may be employed to haul the cans, being 
paid bv the milk dealers. The farmers own the cans in which they 
deliver their milk and clean cans are returned, the cleaning being 
done by the milk dealers. The milk is rarely loaded on the trains 
in the farmers' cans. At the simplest of the stations the milk is 
emptied from the farmers' cans, mixed, cooled and poured into the 
40 quart cans for shipment. At some of the stations, however, the 
milk is clarified, pasteurized, blended and bottled or put in 40 quart 
cans. The bottling is done entirely at the creameries, about one-third 
being bottled and the other two-thirds being shipped in the 40 quart 
cans for supplying large customers. As indicated by Whitaker the 
low fat standard of 3 per cent in the State for milk makes it possible 
for the dealers to skim the milk and then standardize the product 
which they sell to exactly 3 per cent. Some of the producers have 
complained that an injustice is thus clone them. 

The milk stations are located from 2 to 6 miles apart along the 
railroad. The cans are returned dirty to the creameries and are 
there cleaned. They are often very filthy on returning but there are 



144 

good facilities at the ceameries for cleaning them. 

A uniform type of car is used in shipping milk to New York City. 
It is shaped like an express car and built as a refrigerator car with 
only one compartment. There is a trap door in the roof for loading 
ice and ventilating apertures near the bottom. The railroads retain 
entire control of the cars and look after the icing and other details 
in the care of the milk enroute. The milk cars may be attached to 
regular accommodation trains or special milk trains may be made 
up in approaching Greater New York. At the small stations the 
train is stopped to load the milk directly from the creamery, while 
at the large stations a whole loaded car may be waiting for the train. 
The transportation rates are adjusted according to the zone system 
and are as follows: up to 40 miles 23 cents per can of 40 quarts, 
between 40 and 100 miles 26 cents, between 100 and 200 miles 29 
cents, and 200 miles or over 32 cents. The rate on cream is 18 
cents more per can than for milk. Nearly all milk trains running to 
New York reach the city between 10 and 11 p. m. There are no 
arrangements at the railroad terminals for the treatment of milk. 
The wagons are on hand at the arrival of the trains and haul the 
milk away to the different parts of the city. 

Milk Supply of Boston. 

In Boston distinction is made between car-milk and wagon-milk. 
About 80 per cent of the car-milk is handled by five wholesalers who 
are known as contractors. These men lease cars of the railroads, 
buy the milk in the country, maintain milk stations at the city ter- 
minals and sell the milk to distributors and retailers. The con- 
tractors have lately entered the retail field and appear to have an under- 
standing with one another so that as Whitaker states two or three 
men can determine all important points in the milk business of 
Boston. The milk contractors also do a large cream business, but 
much of the cream supply of Boston comes from special creameries 
in Maine which began as butter factories but gradually drifted into 
the cream business. The can used in the milk trade of Boston holds 
8V2 quarts. It is supposed to hold 8 quarts after being battered with 
use. 

The milk contractors of Boston pay a "milk" price for all that 
they sell as such and a "butter" price for the surplus. This arrange- 
111 en t has caused much controversy between the dealers and the pro- 
ducers. The contractors fix the city price of milk for the producers 
and maintain a scale of discounts for the transportation of each can 
according to the distance as follows : between 17 and 23 miles from 
Boston 6 cents, between 23 and 36 miles 7 cents, between 36 and 56 
miles 8 cents, between 56 and 76 miles 9 cents. The discount increases 
one cent for each additional 20 miles. Some discontent has been 
caused by this plan for the reason that the farmers are unable to 
find out the cost of transportation. In 1905 the city price for milk 



145 

was 3 7 1/2 cents per can. At first wooden pings were used exclusively 
as stoppers for the cans. As these became checked with use it was 
found impossible to sterilize them properly. 

Cans and plugs were returned to the farmers dirty and are sup- 
posed to be washed by them. This has formed a prolific source of 
trouble in the milk industry of Boston. The farmers claim that the 
cans are often in an unspeakably filthy condition when they are 
returned to them. It is asserted that consumers use the cans for slops, 
kerosene oil and every conceivable purpose. On the other hand com- 
plaint is made of the improper cleaning of the cans by farmers. The 
wooden plugs can not be perfectly sterilized without thorough boil- 
ing or steaming. ISTot all farmers' wives have facilities for such work. 
A reaction in favor of tin covers in place of the wooden plugs set 
in but it was soon found that the wooden plugs fit tighter and prevent 
leakage better. Moreover with wooden stoppers the cans may be 
conveniently stacked up on one another in the cars. At present the 
tendency is in favor of wooden plugs. In 1905 the farmers agreed 
to allow the contractors one half cent per can for washing them. 

The system of certified milk has not been adopted in Boston. The 
only milk of special quality furnished to the city is delivered directly 
by large producers. Morning's milk produced near the railroad is 
taken to the cars without cooling but night's milk is supposed to be 
cooled to 50 °F. before leaving the farm. . The temperature of the 
milk as it arrives at the trains is sometimes taken by the contractor's 
agent and a record kept. The milk is loaded on the cars by the 
farmers. 

The Boston milk cars are of a special type. The length is 48 feet 
inside measurement. Each car has an office in the center, a door 
at either end and eight closets 3 1-3x4 feet with two shelves carrying 
3 tiers of cans each, or a total capacity of 720 cans. On some days 
additional cans are placed outside of the closets, making the number 
up to 1000. Each car carries two to four tons of ice at the start. 
The men in charge of the cars are in the employ of the contractors. 
As a rule the cars start at 5 or 6 o'clock in the morning and are 4 
or 5 hours on the road. 

About 50 cars of milk reach Boston daily. The trains are met. at 
the station by the milk peddlers and retailers who hurry the milk 
away to their places of business. The peddlers mix the milk to 
produce a uniform quality and bottle it in their own establishments 
which are often somewhat defective from a sanitary standpoint, The 
contractors' receiving stations are fitted with the necessary apparatus 
for cooling and holding over surplus milk, and in some cases with 
butter and cheese making machinery. 

Milk Supply of Philadelphia. 

The milk consumed in Philadelphia comes from Pennsylvania, 
2sTew Jersey, Delaware and Maryland. There are no special cars, 



146 

ordinary baggage or express cars being used. The cars are usually 
attached to passenger trains, and no attempt is made to refrigerate 
them. The farmers for the most part own the cans, which hold 40, 
30, or !20 quarts, and vary greatly in shape. The milk dealers buy 
the milk at the city terminals and the farmers pay for railroad trans- 
portation by a system of tickets one of which is attached to each can. 
Tiiis plan has the advantage that the small and large producers are 
on an equal footing as far as the rate of transportation is concerned. 
The milk dealers, incorporated in an organization known as the 
Philadelphia Milk Exchange, fix the price paid to the farmers from 
month to month. There is no middleman between the dealer and the 
.consumer in the milk business of Philadelphia The dealer delivers 
the milk to the consumer. 

Most of the milk trains start from 5 to 6 o'clock in the morning 
and arrive at the city between 7 and 9 a. m. Since the milk is thus 
onlv two or three hours on the road it is considered unnecessary to 
refrigerate it en route. The dealers, however, must have facilities 
for the mixing, bottling and cold storage of their milk. The great 
number of such establishments and the variation in their sanitary 
condition put a large amount of work and responsibility upon the 
milk inspector. Nevertheless there is certified milk sold in Phila- 
delphia which contains as a rule only 500 to 1,000 bacteria per cubic 
centimeter. 

Milk Supply of Othek Cities. 

The territory about Chicago is well supplied with railroads. The 
milk hauls are short, the longest being about 140 miles, and baggage 
cars attached to passenger trains are used for carrying the milk. For 
a few of the longer hauls an excellent type of refrigerator car is in 
service. Most of the milk arrives in Chicago from 9 to 11 A. M. 

The immense quantity of brewery byproducts in St. Louis available 
as feed for cows makes it possible to maintain profitably about 8,000 
cows within the city limits. This milk sells for somewhat less than 
that brought in by railroad. The longest haul of milk for St. Louis is 
perhaps 150 miles. Ordinary baggage cars are used and there is 
little need of rerfigeration. 

The milk supply of Baltimore comes from dairies in Maryland 
and Pennsylvania within 50 miles of the city. The milk arrives 
from 1 to. 9 A. ML There is great variation in the rates charged by 
the different railroads. There are but a few refrigerator cars in the 
milk service. For the most part baggage cars are used attached to 
local trains, and are cleaned from two to four times per month ac- 
cording to the season. 

The Cleveland milk supply comes entirely from Ohio, within a 
distance of 60 miles, and arrives in the city either in the early morn- 
ing or the evening. No refrigerator cars are used either by the 
steam, or electric roads. Along the electric lines milk-stands are 



147 

erected at every crossroads. For the average haul the freight rate is 
15 cents per 40-quart can. 

All railroads make the same rate for shipping milk to Buffalo, 
even from a distance of 80 miles, 15 cents for a 40-quart can. The 
rate on cream, however, varies greatly on different railroads. Doane 
made a study of the milk supply in 29 cities in 9 southern States. 
In general it was found that the consumption of milk and cream 
is very small as compared with the northern cities. Throughout the 
South there is a large demand for ice cream and buttermilk. Much 
of the ice cream is made from whole milk, cream shipped from north- 
ern states or from condensed milk. In many localities there is more 
call for buttermilk than for sweet milk. There is not enough true 
buttermilk to supply the demand and consequently much of the so- 
called buttermilk in southern cities is skimmilk allowed to sour and 
then churned for a few minutes. 

There are no regular milk trains in the South. Nearly all of the 
milk is produced within the city limits or on the immediate outskirts, 
and is easily delivered by wagon. As a rule the cows are milked very 
early in the morning and afternoon and the milk delivered at once to 
the consumers without any attempt at refrigeration. This plan is 
fairly satisfactory for the morning milk but the afternoon delivery 
is likely to suffer from the effects of heat. In such a simple system 
there is little unnecessary handling of the milk, but in midsummer 
the temperature of the air may be nearly that of the milk when 
drawn. Obviously therefore milk may be delivered almost at a body 
temperature although it is three or four hours old and nearly ready 
to turn sour. In hot climates the warmth of milk is not necessarily 
an indication of freshness. 

In Richmond, Va., there are two large city milk depots which 
handle most of the milk. The farmers deliver to these dealers as 
soon as possible after milking. Here the milk is cooled at once and 
delivered to the consumers about 8 to 15 hours after its receipt by the 
dealers. In Memphis, Norfolk and certain other southern cities the 
conditions surrounding the transportation and sale of milk are about 
all that could be demanded. For the most part,, however, the people 
need to be aroused and suitable inspection laws passed before a really 
good milk supply can be had. 

Concentration and Cooperation in Milk Business. 

From the above brief discussion it is apparent that the sanitary con- 
trol of the transportation and sale of milk is a complicated problem. 
The health officers who are entrusted with the supervision of the 
city milk supply find it necessary to begin with the cows, examine 
the buildings and premises, note the method of milking and handling 
the milk, follow the milk on its journey to the city whether by wagon 
or train and inquire closely into the treatment which milk receives at 
the hands of the dealers and peddlers. If milk is allowed to become 



148 

filthv or infected before it leaves the farm no amount of care in 
transportation can protect the consumer Adequate refrigeration 
en route, however, will prevent the too rapid development of bacteria 
and thus keep the milk from souring- before it reaches its destination. 
Neglect at any point in the transportation of the milk from the farm 
to the consumer endangers the healthfnlness and keeping quality of 
the milk. 

Milk should be cooled down to 50 °F. or lower at the farm. If it 
is brought to the train without cooling refrigerator cars are required 
to prevent premature souring. If the milk has a temperature of 
50 °F. when delivered at the station and the railroad trip is not more 
than a few hours, refrigeration en route is not absolutely necessary. 
Such milk must be cooled at once, however, upon reaching the city. 
If tne milk has been cooled at the farm and kept cool en route it is 
safe to omit refrigeration during the two or three hours necessary 
for delivery. It is not safe for the consumer to make any assumption 
regarding the care which the milk has received before it reached him, 
unless he is thoroughly familiar with the whole system and knows 
the methods of the farmers, the conditions of transportation and the 
dealer's plan of handling milk. Under any circumstances the house- 
holder should keep the milk cool from the time of its receipt till it 
is used. Some precaution may have been omitted. The milk may 
have been too much exposed to the sun in the farmer's wagon. It 
may have been shipped in a car without refrigeration and if so the 
temperature may have been 95 °F. inside the car. An unusual amount 
of dirt may have gained entrance to the milk at the farm, or the 
dealer may have left the can open and thus allowed dust to fall in 
the milk. 

The tendency of the times in all lines of business is toward concen- 
tration. It can not be denied that many advantages both from a 
business and a sanitary standpoint would accrue to the milk industry 
from still further consolidation and centralization. According to the 
present system of supplying milk to cities there are too many men 
concerned who are partly but not entirely responsible for the sanitary 
management of the business. When inspectors find samples of de- 
fective milk they may punish the man in whose possession it was 
found but he in turn may claim that the insanitary condition was due 
to the carelessness or ignorance of others. It seems desirable there- 
fore that some one man or incorporated body of men should be ulti- 
mately and entirely responsible for the sanitary condition of the 
general milk supply of each city. The nearest approach to such a 
centralized system in the milk business is seen in New York where 
each milk dealer has complete control of the milk which he handles 
from the time when the farmer delivers it at the creamery till it 
reaches the consumer. The dealer has to assume the responsibility 
for the good condition of milk which he sells and he in turn tries to 
control by business contracts the conditions on the farms from which 



149 

he buys milk. This plan operates in a fairly satisfactory manner but 
there are frequent controversies between the farmers and the dealers. 
The farmers cannot learn the cost of transportation and therefore are 
never able to determine whether they receive fair treatment from the 
dealers. 

Most of these troubles could be solved and an important step taken 
toward the procurement of an ideal milk supply for cities by estab- 
lishing a general cooperative organization among the farmers who 
furnish milk to each city. This would involve the formation of a 
cooperative association of each community of dairymen, who would 
be represented by delegates in the council of the general federation of 
cooperative dairymen's societies in the city to which the milk is 
furnished. The farmer would then become a producer, dealer, dis- 
tributor and retailer. He would control the milk in all its stages 
from the feed used in producing it in the cow through, its transporta- 
tion by railroad and wagon till it is placed in the icebox of the con- 
sumer. All controversies about prices and transportation would be 
eliminated, and the problems of the milk inspector would be much 
simplified. 

One of the curses of the milk business in many cities is the part 
which grocerymen and small middlemen play. It is too often true 
that these men have no facilities for properly caring for milk. Milk 
is merely one of the many products which they sell and is the one to 
suffer most from lack of attention. If the farmers should organize 
on a cooperative basis so as to control both production and distribution 
the business would fully justify improvements to meet sanitary 
requirements all along the line. Better dairy buildings could be con- 
structed, more attention given to the health of the cows, excellent milk 
stations established, modern refrigerator cars operated, and unexcep j 
tionable receiving stations and delivery wagons could be put in service 
in the cities. The inspector would then have but one concern to deal 
with. In case of a defective sample of milk being discovered it would 
at once become the duty of the cooperative association of dairy farmers 
to trace the sample to its origin and warn or punish the offender. 



150 



CHAPTER VIII. 

REFRIGERATION 

Cold is the best and most sanitary means of preserving all food 
products including milk. If no pathogenic bacteria are present, cold 
is all that is necessary to preserve milk in its best condition. If on 
account of the fear of infection the milk is previously pasteurized, 
cold must be applied to keep the milk in condition after pasteurization. 
Before discussing the methods of refrigeration in use we may briefly 
mention the physical and chemical properties of milk which determine 
its reaction to cold and the effect of cold upon it. 

The specific heat of whole milk is about .94, of skimmilk .95, of 
whey .95 and of cream .87. Some differences are observed in the 
determination of specific heat by different investigators but according 
to Kasdorf whose results have been freely utilized in this chapter the 
specific heat of milk is so nearly that of water that for practical pur- 
poses it may be taken as the same. The expansion coefficient of 
milk is affected by the temperature. Between 40° and 60 °F it is 
greater than that of water and the maximum density is reached at 
26.5 °F. The cohesion and viscosity of milk increase as the temper- 
ature is lowered. 

The freezing point of milk is slightly lower than water, being 
about 31.5°F. The addition of water causes the freezing point to 
approach that of water. Skimming milk does not affect the freezing 
point. Advantage may be taken of this fact to detect the addition of 
water to milk. Parmentier found, that the limit, of variation of the 
freezing point of normal milk was 30.97° to 31.02°F. When eight 
volumes of water are added the freezing point is 31.9 °F. The addi- 
tion of borax or soda to milk also lowers the freezing point somewhat, 
and increasing acidity has the same effect. The freezing point falls 
.2°F. for every 24 hours the milk is held. 

The application of cold to milk changes its physical and chemical 
properties. As a can of milk is frozen the solid constituents of the 
milk with the exception of the fat are gradually forced out so that 
■the fluid portion contains more casein, milk sugar and, ash than the 
ice milk while the latter carries a high percentage of fat. During 
the process of freezing the fat rises and is caught in the forming ice 
on the upper surface of the milk. In a partly frozen can of milk, 
therefore, the fluid portion has a higher specific gravity than the 
frozen portion. When a given quantity of milk is frozen into a solid 
block of ice the upper layer of the ice is composed almost entirely of 
fat while the center and lower portion contains the greater part of 
the milk sugar, casein and ash. When frozen milk is thawed out the 



151 

layer of fat at first remains separate and thorough, shaking or stirring 
is required to' restore a condition of fat emulsion such as is seen in 
normal milk. Flakes of fat and casein may appear in such milk and 
it is often impossible to get the fat distributed with perfect uni- 
formity. The flakes are more conspicuous the longer the milk has 
been frozen. If milk is kept in an ice form for three months or more 
a considerable number of flakes appear after thawing and form a 
sediment. In addition to the flakes containing a large percentage of 
fat, irregular spherical granules are found in milk which has been 
frozen. These are apparently due to pressure in freezing. Milk which 
has been sterilized by heating before freezing can not be made to as- 
sume a normal condition after thawing. In this respect homogenized 
milk behaves in a very similar manner. 

The extent and intensity of the disturbance in the relation between 
the different constituents of milk depends in large part upon the 
rapidity with which the milk is cooled and frozen. If milk is frozen 
in bottles or other vessels as rapidly as possible it readily assumes a 
normal condition after thawing. Milk in large cans, however, can 
not be frozen so quickly and after thawing shows neither the 
appearance nor the flavor of fresh milk. There is thus a distinct 
practical advantage in freezing milk in small vessels. The keeping 
quality of milk once frozen and thawed depends upon the care and 
cleanliness with which it was handled before freezing. The flakes 
of casein and fat mentioned above are readily dissolved by the appli- 
cation of heat after the milk has been in a frozen state for three 
weeks, less quickly after 4 to 5 weeks and not at all after 4 months. 
There is thus a practical limit to the time during which milk may 
be kept frozen. 

Methods of Refrigeration. 

The methods of refrigeration as applied to milk and its products 
include the use of cold water, ice, freezing mixtures, gravity brine 
system and various forms of artificial refrigeration involving the 
use of ammonia, carbon dioxid and other substances. The choice' 
between natural and artificial means of refrigeration will depend in 
every case upon the local conditions. 

Wherever available, cold water may always be used to* help in the 
process of refrigeration. The extent to which milk or milk products 
may be cooled by water depends naturally upon the temperature of 
the water. Well water has a fairly constant temperature the year 
around. This ranges in most instances from 50° to 55 °F and the 
water will cool milk down to within two or three degrees of its own 
temperature, or on an average 56°F. More often, however, the 
lowest temperature which can be produced in milk by cold water is 
60 °F. This means a lowering of 40 degrees from the body tempera- 
ture and may be accomplished most cheaply by water at least in most 
instances. Then for cooling milk and its products to a temperature 



152 

suitable for long keeping recourse must be had to other sources of 
cold. Running water is not nearly so effective as melting ice for 
cooling purposes but there is economy in exhausting the effectiveness 
of the cold water before resorting to the more expensive methods of 
refrigeration. 

Ice furnishes the simplest means of producing low temperatures in 
milk. It cannot be placed directly in the milk except in the form of 
ice-milk ; otherwise it would be a form of adulteration and might 
contaminate the milk. Moreover ice melts rather slowly and its 
refrigerating effect is not exercised rapidly enough unless salt is 
added to it to make it melt faster. Ice may also be used to reduce 
water nearly to a freezing temperature after which the cold water 
may be applied to the refrigeration of milk. The refrigerating effect 
of ice is exercisd only when it melts. It then absorbs heat from sur- 
rounding objects. The temperature of the water resulting from the 
melting of the ice and salt mixture in an ice cream freezer is often 
below zero. The combinations of ice and salt are known as freezing 
mixtures. 

The effectiveness of a system of refrigeration is judged largely 
by the rapidity with which it cools milk. On this point and also on 
the point of economy natural and artificial refrigeration may be best 
compared after both systems have been described. 

Ice used alone melts too slowly and therefore exerts its cooling 
effect too slowly for farm, creamery or storage use. Freezing mix- 
tures of cracked ice and salt, however, soon reach a temperature of 
zero F. They may be used on a small or large scale. The larger 
the proportion of salt the more rapid the melting. But it is necessary 
to practice economy in the matter, and while an ideal proportion 
would be two parts' of ice to one of salt the common practice is to 
use one part of salt to ten or twelve of ice. The ice may be cracked 
and the brine pumped to the milk cooler by hand or by machinery 
according to the amount of milk to be cooled. A great variety of 
milk coolers of the flat or cylindrical type for the utilization of 
freezing mixtures have been put on the market in this country, 
England and continental Europe. Some of these coolers are double, 
the cooling process starting with cold water and finishing with brine. 
A saving is thus effected in the ice bill. A system much used in Eng- 
land includes an oak tank for holding the freezing mixture which is 
pumped to the cooler by hand. The brine returning from the milk: 
passes through a copper coil in the upper part of the tank where it 
ib cooled before being pumped back to the milk coils. In this machine 
salt and ice are used in the proportion of one to three. The mixture 
is kept stirred by a plunger connected with the pump. 

In Berlin a cylindrical milk cooler has been devised using salt 
and ice in the proportion of one to six. An ice crusher is attached to 
one side of the brine tank, and the brine is pumped through the cooler 
so that it returns to the tank with the original force of the pump. This 



153 

agitates the brine and obviates the necessity of a copper coil and 
plunger in the tank. 

In this country a modification of the brine apparatus has been 
devised by Cooper and is known as the gravity brine system. Cracked 
ice and salt in a tank produce an intensely cold brine which circulates 
til rough the cooling, refrigerating or freezing rooms as a result of dif- 
ferences of temperature at the two ends of the system. This system 
is therefore automatic and it is claimed that by its use a freezing 
room may be kept at a temperature of 15 °F. 

If desirable under any circumstances milk or its products may be 
placed in cans directly in the brine tank and removed after cooling. 
This involves the handling of cans and spilling the brine about the 
floor. It is therefore impossible to keep a dairy establishment in as 
good sanitary condition as by a system in which the brine is carried 
to the milk in pipes. The freezing brine is not always produced by 
mixing salt and ice. For example in Toselli's machine the freezing 
agent is a mixture of water and ammonium nitrate which causes a 
reduction of temperature to the extent of 40 degrees F. In an ap- 
paratus devised by Siemen a mixture of water and calcium chloride 
is used. This will reduce the temperature about 30 degrees F. 
Snow melts rapidly and therefore may be used in the place of ice 
wherever available in combination with some chemical. Among the 
chemicals used for this purpose we may mention sodium chloride, 
ammonium chloride, calcium chloride, dilute sulphuric, hydrochloric 
or nitric acid, nitrate of ammonium or potash, phosphate and sulphate 
of sodium, etc. Some freezing mixtures contain neither snow or ice 
but depend for their cooling effect upon the solution of a chemical. 

One of the simplest forms of apparatus devised for cooling cream 
consists of a tank and a frame for holding the cream can which is 
revolved in the spring water or ice water in the tank. This apparatus 
is not very effective. Better results are obtained by the use of ap- 
paratus in which the milk or cream is allowed to trickle over a corru- 
gated metal surface on the other side of which the freezing mixture 
is maintained either in a stationary or moving condition. Cooling 
apparatus using freezing mixtures with a direct current are less 
effective than those in which a reverse current is maintained. In 
machines with a direct current the freezing mixture and the milk 
flow in the same direction while in machines with reverse current 
they flow in opposite directions. By the use of a reverse current the 
greatest difference of temperature is maintained between the freezing 
mixture and the milk. If the reverse current is adopted a smaller 
quantity of freezing mixture and a larger cooling surface are required. 
For this reason the reverse current is utilized in cooling milk. A 
great variety of such coolers have been patented, their essential 
feature being a flat or cylindrical corrugated metallic surface over 
which the milk trickles while being cooled, by the freezing mixture on 
the other side of the metallic surface. Some of these machines are 



154 

designed especially for cooling pasteurized milk or cream. They are 
made of all sizes to adapt them to a large or small business. The 
chief advantages of this system lie in the fact that the milk is cooled, 
very rapidly on account of the thin layers in which it flows over the 
cooling surface, and the ease with which they may be cleaned. In 
some refrigeration plants use is made of a combination of the brine 
system and the expansion of ammonia, which is one of the chief 
physical principles utilized in refrigerating by the artificial methods 
described in the next paragraphs. 

Artificial refrigerating apparatus depends for its effectiveness 
chiefly upon the two laws of physics that compressed air becomes 
colder by expansion and that fluids extract heat from surrounding 
substances in vaporizing. Several refrigerating systems have been 
devised to utilize these laws, such as the vacuum process, the com- 
pression process, water cooling towers, the absorption process, and 
the cold air system. Compression machines are the most important 
in the refrigeration of dairy products. These machines utilize sul- 
phurous ether, methyl ether, carbon dioxid, sulphurous acid and 
ammonia, but chiefly ammonia. The ammonia machines in this country 
are of both the compression and absorption types, and the compressors 
operate under a wet or dry system. As described by Haven and Dean, 
"in wet compression some of the ammonia enters the compressor 
cylinders in a liquid state, the heat developed during compression 
being used up in converting the liquid into vapor, and consequently 
there is a saturated vapor at the end of the compression which has a 
boiling point corresponding to the condenser pressure. In this type 
no water jacket is required around the ammonia cylinder. In dry 
compression the ammonia entering the compressor cylinder is all in 
a gaseous condition, so that the heat developed during compression, if 
no water jacket is used, superheats the gas several hundred degrees 
above the temperature corresponding to the condenser pressure. A 
water-jacket surrounds the ammonia cylinder, however, and absorbs 
the heat, permitting cylinder lubrication." 

Both the ammonia and carbonic acid machines are perfectly satis- 
factory in operation in mort instances but occasionally prove less 
certain in their results than the sulphurous acid machines. This is 
due to the fact that they operate under a pressure of 10 to 70 at- 
mospheres, while the pressure in the sulphurous acid machines is only 
two or three atmospheres. Another advantage in favor of the latter 
machines is that the compressors require no special oiling since the 
sulphurous acid is of an oily nature. On the other hand these ma- 
chines suffer from the disadvantage that from 20 to 60 per cent more 
energy is required for the same amount of refrigeration than when 
the ammonia machines are used. In the United States ammonia has 
practically replaced all other gases for purposes of refrigeration. 

In the ammonia compression machines the ammonia is forced under 
high pressure into a system of coiled tubes where it is vaporized, 



155 

thereby absorbing the necessary latent heat from the surrounding 
material (brine, water or air). The gaseous ammonia is then drawn 
into a compressor where it is brought under pressure to a liquid state 
and then forced into a second system of coiled tubes known as the con- 
denser where the heat is carried away by flowing water. The fluid 
ammonia is then carried back to the vaporizer and the cycle begins 
anew. 

The absorption machines also use ammonia but the ammonia is 
vaporized under the direct action of heat rather than by the use of 
power. As described by Tayler these machines include apparatus for 
distilling, condensing and liquefying ammonia; a refrigerator, ab« 
sorber, condenser, concentrator and rectifier; and pumps for forcing 
the liquid from the condenser into the generator. Haven and Dean 
describe the operation of these machines as follows: "The generator 
contains a solution of strong ammonia liquor in which the steamcoils 
are immersed. The ammonia in solution, having a lower boiling point 
than water, is partially vaporized by the heat from the steam-coils, 
leaving a weak solution of ammonia. The gas thus liberated passes 
through the analyser to the rectifier. Whatever water-vapor may have 
been carried along with the ammonia gas is condensed here and drips 
back into the generator. From the rectifier coils the gas passes into 
the condenser, and is collected in the receiver, from which it is ex- 
panded into the cooler or refrigerator coils. The gas from the cooler 
passes to the absorber and there meets the incoming weak liquor from 
the generator and is absorbed, forming strong liquor. The strong 
liquor is pumped through the exchanger into the top of the analyser and 
runs down over its pans to the generator." 

The artificial refrigerating machines may be constructed on a large 
or small scale but are chiefly employed in cooling compartments for 
cold storage, which are called coolers if the temperature is 30 °F. or 
above, holding freezers if 10 °F. or lower and sharp freezers if zero 
to 20° below zero F. The absorption system is of little practical im- 
portance in the refrigeration of dairy products. It has been shown 
experimentally that the effectiveness of the compression machines is 
nearly proportional to the weight of the gas discharged, and that their 
ice-making capacity is about 60 per cent of their refrigerating capacity. 
The same machine may be used for making ice, refrigerating or both. 

In one of the simplest compression machines for utilizing carbon 
dioxid in the place of ammonia the chief parts are a gasometer, pump, 
cooler, drier, condensing coil, and refrigerating tank. The carbon 
dioxid is drawn into the pump where it is liquefied, and the heat thus 
produced is absorbed in the cooler. The gas is then allowed to expand 
in the refrigerating tank and is passed back to the gasometer. Carbon 
dioxid unlike ammonia is non-corrosive to the piping. Moreover it is 
non-inflammable and has a high specific gravity, thus giving a high 
heat of vaporization. Compression machines for carbon dioxid must 
be operated under high pressure since it is difficult to liquefy the gas. 



156 

The energy required for operating with carbon dioxid is much more 
than is the case with ammonia. In large establishments the unit of 
refrigeration is the ton, or the refrigerating capacity of a ton of ice 
melting in 24 hour, which equals 284,000 British thermal units. 

In most cases the relative economy will determine whether refrig- 
eration is to be done with ice or machines. In the northern states if 
creameries or other dairy establishments are located near ponds or 
rivers it may be possible to store ice for a dollar or less per ton. At 
that price ice is cheaper than artificial refrigeration for a business of 
ordinary proportions. In all cases where ice is expensive and the 
amount of milk handled daily more than 15,000 pounds a refrigerating 
plant will prove a profitable investment. The advantages and disad- 
vantages of mechanical refrigeration have been well summarized by 
Professor Erf in the following paragraph. 

The chief disadvantages are that a large capital must be invested, 
the machines must be operated daily unless storage tanks are provided, 
operating expenses for coil, oil, ammonia and repairs are considerable, 
the excessive dryness in the refrigerators often causes great shrinkage in 
the products, there are risks for accidents due to breakage of machines 
and delay of repairs and lastly we have the expense of pumping water 
for condensing ammonia. On the other hand the important advantages 
of artificial refrigeration over natural ice are that there are no risks 
in securing cold when needed, little variation in the cost or refrigera- 
tion, better control of the refrigerator, the possibility of obtaining a 
lower temperature, a dried atmosphere and less liability of mold, less 
disagreeable work such as handling ice, better sanitation, no danger 
of contamination from impurities in river ice, better cream ripening 
and economy of space in the cooling rooms. 

If the gravity brine system should be adopted, however, Cooper 
stoutly maintains that there would be "absolutely no risk to run in 
securing cold whenever needed. Any temperature may be practically 
obtained down to 15 °F. The refrigeration would be under fully as 
good control and a more uniform temperature could be obtained than 
by the use of refrigerating machinery. The moisture in the at- 
mosphere of the cold room could be carried at any temperature desired 
and under as good control as with the mechanical system. The amount 
of disagreeable labor required, should an ice crusher and ice elevator 
be used, would be very small indeed. The cold room can be kept as 
clean as with any system. Impurities in the ice would have no in- 
fluence on the air of the room for the reason that the air does not 
come in contact with the ice." 

It would lead us too far from the purpose of this volume to go into 
details regarding the construction of ice houses or refrigerating plants, 
the materials to be used or methods of securing proper ventilation, 
absorption of moisture, insulation and circulation of cold air. These 
matters belong to the field of the architect and builder. In the follow- 



157 

ing paragraphs we call attention to some of the special applications 
of refrigeration to milk and its products. 

The creaming of milk is greatly influenced by the temperature. A 
richer cream is obtained under a high temperature and the process 
takes place more rapidly. On the other hand the rapid souring may 
give a bad flavor to the cream and the premature curdling of the milk 
may prevent all of the fat globules rising to the surface. These facts 
induced the use of ice or some other form of refrigeration in the 
creaming of milk. It has been found that the lower the temperature, 
within reasonable limits the larger the amount of cream obtained and 
on this account refrigeration in the field of dairying was first applied 
to the ripening of cream and the creaming of milk. These matters 
are discussed in the chapter on Milking and handling of milk. 

Ideal refrigeration requires that the milk be cooled down as soon 
as possible to a temperature at which lactic acid bacteria can not grow. 
Lf cream is to be used as such rather than for making butter it retains 
its aroma and flavor longer the lower the temperature provided the 
cream is not frozen. For this purpose 39 °F. is a good temperature. 
Usually milk is held at 50 °F. but 40° F. is better. Skim milk direct 
from the separator should be hept at the same temperature. 

Fkozeist Milk. 

Since 1888 experiments have been made in freezing milk to pre- 
serve it in a fresh condition. In 1894 it was shown that by adding a 
certain proportion of frozen milk to a can of milk and packing it in 
sawdust the whole mixture could be kept fresh for two or three weeks. 
At the earlier date Guerin's plan of freezing milk at a temperature 
of 2 C F. below zero was adopted by a large dairy which furnished milk 
for Paris. In 1893 and 1894 a Danish engineer patented a scheme 
for freezing milk and made application for many other patents which 
were not granted. The Casse system was adopted by a Danish dairy 
company which furnished daily 30,000 pounds of milk to Copenhagen. 
Their plan was to freeze milk in cakes weighing about 25 pounds and 
place them in cans holding about 500 pounds of milk. One cake was 
placed in each can at night and the next morning the cans were filled 
with fresh milk and closed air-tight before shipping. When treated in 
this manner the milk kept in good condition for several weeks being 
drawn at- will. The contents of the cans were thawed out by placing 
them in vessels surrounded by hot water coils. It is claimed that 
the currents thus produced mixed the constituents of the milk and 
preserved the original flavor and composition. Butter made from such 
milk, however, was unsatisfactory. In 1898 an establishment near 
Zurich began to furnish 10,000 pounds of milk-ice daily to that city. 
It has been found to keep nine days, sweet and unchanged. In 
Copenhagen the demand for milk-ice has increased and the public 
prefer it to other milk for the reason that the chilling as soon as 
possible after milking preserves the original aroma and hinders the 



158 

growth of micro-organisms. It is of advantage to dealers since surplus 
milk can be stored for some time and used as needed. 

In a chemical study of frozen milk Siegfeld. found that the upper 
portion of the block of milk-ice contained 8.45 per cent of fat and the 
lower portion 2.11 per cent. The percentage of total solids in the milk- 
ice increased toward the center of the cake. When skim milk was 
used the outer portion of the frozen cake contained 7.03 per cent of 
solids and the central part 15.9 per cent. The freezing of cream 
resulted in decreasing the time required for churning. Farrington 
found that when 25 per cent of a sample of milk was frozen the fat 
content of the liquid was about .5 per cent higher and of the ice about 
one per cent lower than that of the original sample. When 40 to 50 
per cent of the sample was frozen there wias no great difference in the 
fat content of the liquid and iced portions. 

In Germany the repeated application for patents on processes for 
making milk ice has led to legal definitions according to which "cold 
milk" means milk to which milk ice has been added, and "milk ice" 
means frozen milk. Casse's system has been introduced most ex- 
tensively in Denmark and Sweden. Opinions differ widely as to the 
adaptability of the method and the results obtained by its use. One 
great objection to any method, in which half of the milk is frozen is 
the cost. It requires about 140 calories to freeze 2*4 pounds of milk 
and of this number only 80 can be saved in melting while 60 are 
entirely lost. The only way by which a saving may be made is to 
reduce the amount of frozen milk added to each can. A plan was 
devised by Helm to meet these requirements and has been put into 
use in several German cities. The milk is first pasteurized, then 
cooled to 35 F. after which varying quantities of mill?: ice are added 
according to the distances to which it is to be shipped. It was soon 
found that when milk was pasteurized and then refrigerated with 
milk ice one bad result of pasteurization became apparent. As a 
result of pasteurization the lactic acid bacteria are destroyed and this 
allows the putrefactive organisms to decompose the milk albumen. 
fSuch an outcome may be prevented by adding a small quantity of pure 
cultures of lactic acid bacteria after the milk has been cooled. 

As already indicated one of the serious objections to the commercial 
adoption of the milk ice system lies in the fact that in freezing the 
uniform distribution of the different solid constituents of the milk is 
disturbed. The larger the vessel in which the milk is frozen the 
greater the variation in the composition of the different portions of 
the milk. On this account it is obviously desirable to use small cells 
or cans for freezing. This idea, however, should not be carried too 
far. About 6 inches is the smallest diameter practicable for freezing. 
The outside of a cylinder of milk is frozen much more rapidly than 
the center. This is due to the fact that the milk solids accumulate 
in the center as the freezing proceeds. Bernstein therefore devised a 
freezing cell in which the central part was occupied by a metallic 



159 

tube. In order to insure the retention of the normal composition in 
all parts of the milk the freezing cell is made heavy enough to hold 
the milk ice at the bottom of the vessel of milk to be cooled. As the 
milk ice melts the temperature differences keep up a constant circula- 
tion of all parts of the milk. 

It has been found possible to obtain frozen milk in the form of milk 
snow by freezing a spray of milk on the outside of a cylinder from 
which the frozen milk is constantly scraped off. This prevents any 
abnormal distribution of the constituents of the milk. Cream may 
be frozen in the same manner but this method of handling it has not 
found commercial acceptance. In Finland the plan has been adopted 
in at least one town. The cream can is placed in a freezing mixture 
immediately after separation and the cream promptly freezes. More 
cream is added after each milking until the can is full, the process 
requiring a week or more for each dairyman. Frozen cream possesses 
a striking resistance to changes of temperature and therefore stands 
shipment well. 

Cold Storage of Butter. 

There is some difference of opinion regarding the proper tempera- 
ture for the cold storage of butter, but the present tendency is decidedly 
toward the use of very low temperatures as compared with those pre- 
viously in vogue. At first a temperature of 35° to 40°F. was consid- 
ered satisfactory. This degree of cold was found sufficient to keep 
butter in a fairly good condition for two or three months. But the 
standards of efficiency for culd storage are higher and the require- 
ments are becoming more severe. Perhaps the majority of dealers 
consider 20°F. low enough for butter. It has been found, however, 
that at zero or below butter keeps well for 9 months or more. Both 
flavor and quality are retained and the loss in weight is practically 
null. For long storage of butter Cooper recommends a temperature 
of 12° to 15°F. It may be found that the grain is injured by storage 
at temperatures about the zero point, but the danger from exposure 
to air will be much less than at higher temperatures. The desirable 
aroma and flavor of butter may best be preserved by applying low 
temperatures and protecting from the air. 

Cold Storage of Cheese. 

Formerly cheese was cured and stored at ordinary temperatures but 
about twenty years ago cold storage began to be applied to this product. 
The whole problem of cold storage of cheese has been most thoroughly 
investigated by the Bureau of Animal Industry and the experiment 
stations in Wisconsin and New York. A preliminary investigation by 
Babcock and Russell in Wisconsin showed that in the ordinary cheese 
curing rooms there is too great a variation of temperature, often 
running as high as 90 °F. and in one case to 104°F. In the experi- 
ments in -curing rooms with regulated temperature it was soon found, 
that the rate of curing is proportional to the temperature, the higher 



160 

the temperature the more rapid the curing. In every case cheese 
cured at high temperatures were inferior to those held below this point. 
P>oth the flavor and texture suffered from the high temperature. The 
loss in weight was found to be greater at high than at low tempera- 
tures, and while the cheese reached maturity more quickly its com- 
mercial period was shorter. In the experiments of the Bureau of 
Animal Industry when temperatures of 40°, 50°, and 60°F. were 
compared the loss of moisture was less at low temperatures, the 
quality of the cheese was better and the cheese kept longer. A tem- 
perature of 40°F. proved better than 34° or 28°F. as determined by 
a careful scoring test. The combination of a low temperature and 
the use of paraffine reduced the loss in weight to a minimum. 

Condensed Milk and MIilk Sugar Obtained by Freezing. 

The customary method of manufacturing condensed milk requires 
the application of heat to drive out the water. It is less costly, how- 
ever, to freeze out the water than to evaporate it by the use of heat. 
As shown by Kasdorf it requires 600 calories to desiccate 2% pounds 
oi milk by heat and only 80 calories to freeze it dry. Moreover when 
heat is apjdied the casein is denatured and the flavor of the product 
is changed. For several years therefore attempts have been made to 
produce condensed milk by the use of artificial refrigeration. Of the 
devices proposed for this purpose that of Giirber is perhaps the best. 
According to this plan the milk is frozen in a centrifuge in such a 
manner that the processes of freezing and thawing are made parts 
of one operation, and the milk ice while in process of formation is 
forced, to give up its solid parts under centrifugal action. GHirber 
has improved his method by the use of an apparatus in which the 
milk is conducted over the outside of a cylinder cooled from the inside. 
The solids of the milk are thus separated out according to the prin- 
ciple of the separation of chemicals from solutions by freezing. 

Some attention has been given to the problem of separating milk 
sugar by means of refrigeration. A device perfected by C. Schmitz 
may perhaps be used for this purpose. Fluids containing different 
substances are frozen by being thrown as a spray into chilled air. A 
number of different substances are thus formed such as salt crystals, 
ice crystals of pure water, etc. The different bodies will have different 
specific gravity and may be separated by blasts of air. 

It has already been stated that in freezing milk suffers a disturbance 
in the distribution of its constituents. The upper layer when frozen 
contains more fat than normal milk, while the other solid parts of 
the milk become concentrated in the still liquid portion. Seyboth has 
taken advantage of this fact in the preparation of hygienic infants' 
milk of any required composition. Special cans have been devised in 
which the desired percentage of fat or other solids in the milk may 
be obtained by regulating the process of freezing. 



161 

The refrigeration of milk during shipment is a rather expensive 
process. A number of refrigerating milk cans have been devised 
some with a central cylinder containing ice and with or without insula- 
tion. For long shipment the can may be placed in a cold brine tank 
in the car. Square cans pack more closely than cylindrical cans. 
Some insulating material may be thrown over the cans. Better 
results will of course be obtained by the use of refrigerator cars. The 
only objection to them is the expense connected with their operation. 
In the United States nearly all refrigerator cars are cooled by ice or 
cold brine. Their extensive use for the shipment of meat and fruit 
is well known to all, and in some cities it has become desirable or 
even necessary to make use of them for the shipment of milk. Their 
use insures the receipt of the milk at the city terminal without, deter- 
ioration. 



162 



CHAPTER IX. 

PASTEURIZATION AND STERILIZATION OF MILK. 

On account of the fact that it is impossible to obtain milk on a 
commercial scale free from bacteria, attempts have been made to use 
chemical antiseptics and to apply heat in order to render milk sterile 
or nearly so after it has been drawn. There are more or less serious 
objections to the use of all chemical preservatives in milk and accord- 
ingly more attention has been given to the perfection of methods of 
pasteurization. Soxhlet was the first to apply pasteurization to the 
treatment of milk, especially for the use of infants. His recommenda- 
tion of this process was made in 1886. In 1889, experiments in 
pasteurization were begun in America, and since that time the pro- 
cedure has gradually gained in favor, although many objections have 
been raised to it from various standpoints. In 1892, sterilization of 
milk in tenement houses in New York was adopted and at present it 
is estimated that about 25 per cent of the total milk supply of New 
York is pasteurized. About one-third of the milk supply of Boston 
is subjected to commercial pasteurization. Pasteurization in hnlh 
is generally practiced in Denmark, Grermany, France, and other 
countries of Europe. This practice is so widespread in continental 
Europe that sanitary officers have been led to doubt the accuracy of 
American investigations regarding the transmission of infectious 
diseases, particularly diphtheria and scarlet fever in milk. Where 
milk is generally pasteurized before use it is obviously impossible 
for it to be an important vehicle in the transmission of these diseases. 

Distinction has been made between pasteurization, which usually 
means the heating of milk to a. temperature of 140 to 185° for a 
variable period, and sterilization, which means the application of heat 
at the boiling point or above for a shorter or a longer period. 

The first matter for consideration in pasteurization is the choice of 
apparatus. If it is merely desired to sterilize milk as thoroughly as 
may be for household purposes without special regard to the maximum 
temperature, the milk may be placed in any clean cooking utensil and 
boiled over a fire for a short time. It is ordinarily not necessary to 
boil the milk but a few minutes since the boiling temperature destroys 
all bacteria except spores and these may not be destroyed even in a 
longer period of boiling. In pasteurization for household purposes, 
the methods may be quite inexact. Milk is placed over the fire in a 
cooking utensil and raised nearly to a boiling point or to a temperature 
ranging from 170 to 185 °F. after which the milk is removed and 
allowed to cool. More exact household methods consist in sterilizing 
the milk in cans or jars placed inside of another utensil containing 



163 

water which is heated to the required temperature. If the milk con- 
tainer is placed in another vessel containing water, it is best to have 
a perforated false bottom so that the milk is entirely surrounded by 
water. The different portions of the milk are thereby heated more 
uniformly. 

The requisites for successful pasteurization have been well stated 
by C. D. Smith. The milk to be pasteurized should be fresh from 
the cow and should be handled in as cleanly a manner as possible in 
order to prevent the entrance of spore-bearing bacteria which are 
largely derived from sources outside of the cow. The milk should 
be brought rapidly to a temperature of 140 to 185 °F. and kept at 
that temperature for 5 to 20 minutes depending on whether the high 
or low temperature is adopted. It is somewhat unsafe to heat milk 
above 160°F. since objection may be raised to a cooked flavor. All 
apparatus used in the pasteurization of milk must be kept scrupulously 
clean and milk must be brought down to a temperature of 50°F. 
immediately after pasteurization and held at that temperature until 
it is used. 

In pasteurizing milk on a large scale, the objection has, been made 
against an intermittent form of pasteurizer that it requires too much 
time and is therefore an expensive apparatus. A number of forms 
of intermittent pasteurizers have been devised but, as stated by 
Russell, they must all be efficient in operation, easy to clean and 
sterilize, simple in construction, economical in use, and safe from 
reinfection. An effective combined pasteurizer and cooler was devised 
by "Russell and was found to give excellent results in destroying patho- 
genic and other bacteria, in milk and in prolonging the keeping prop- 
erty of the milk without producing any disagreeable effects in it. 

Russell and others have made an extended study of the efficiency of 
continuous flow pasteurizers. These machines possess the great com- 
mercial advantages of easy operation and great capacity. The milk 
flows over heated surfaces or through heated pipes in a continuous 
stream and in some of the most improved types the pasteurized milk 
is carried back over the same course along which it entered so as 
partly to warm the fresh milk entering the machine. A great dis- 
advantage of continuous pasteurizers is that the milk is subjected to 
heat for a very short period. In Russell's experiments with a con- 
tinuous pasteurizer it was found that the milk passed through the 
apparatus in about 15 seconds when the machine was running at full 
capacity. Some of the milk, however, was retained in the machine 
for 30 or even 45 seconds. The time exposure to heat was increased 
to 70 to 100 seconds by half closing the inlet pipe, thus making the 
rate of flow about 1,000 lbs, of milk per hour. It is obviously neces- 
sary that the milk should be subjected to the required temperature 
for a definite period of time if pasteurization is to accomplish the 
purpose of destroying a large portion of the bacteria in milk. There 
is no question that the tank or intermittent pasteurizer is more efficient 



164 

in this respect than the continuous pasteurizer, but the prolonged 
retention of the milk in the machine renders the apparatus imprac- 
ticable for use on a large scale. Under proficient supervision and 
with a proper limitation of the rate of flow the continuous pasteurizer 
may be operated so as to give satisfactory results on a commercial 
scale. 

Effect of Pasteurization on the Biology of Milk. 

The chief purpose of pasteurization being the destruction of patho- 
genic and harmful bacteria in the milk, it is of prime importance to 
inquire how effectively this purpose is accomplished. In the use of 
a continuous pasteurizer tested by Russell, it was found that the 
number of bacteria per cubic centimeter after pasteurization ranged 
from 5,000 to 18,000 as compared with a range of 125,000 to 965,000 
per cubic centimeter of raw milk. These figures are for the winter 
conditions. In summer the range of bacterial content after pasteuri- 
zation was 2,900 to 1,000,000 per cubic centimeter as compared with 
1,000,000 to 60,000,000 in raw milk. It is apparent from this 
test that only a certain percentage of the bacteria present in milk 
are destroyed by pasteurization in the continuous machine and if 
the milk is not heated to a temperature of 160 °F. it may contain 
virulent pathogenic bacteria after pasteurization. 

Rogers called attention to the fact that pasteurization to be considered 
efficient should destroy practically all of the bacteria in the vegetative 
stage. This result is accomplished by the application of a compara- 
tively high degree of heat for a short time or by a lower temperature 
for a longer period. In intermittent machines the milk is usually 
held at the chosen temperature for from 1 5 to 30 minutes. 

The tubercle bacillus has been taken as a standard for determining 
the efficiency of pasteurization. When milk is properly pasteurized 
and agitated at the same time so that no film is allowed to form on 
the surface, it has been definitely shown that tubercle bacilli are 
destroyed by an exposure for 15 to 20 minutes at a temperature of 
60°C. (140°F.). In ordinary practice, however, it has been found 
safer to subject the milk to a temperature of 68 to 71° C. In contin- 
uous pasteurizers some experiments have shown that a temperature of 
80° to 85 °C. is required to destroy tubercle bacilli. A great amount 
of attention has been given to a study of the thermal death point of 
the tubercle bacillus in commercial milk. The results obtained by 
different investigators have varied somewhat depending upon the 
kind of apparatus used and the care with which all conditions are 
controlled. Russell and Hastings found that a temperature of 60 °C. 
for 10 minutes was sufficient to render tubercle bacilli nonvirulent 
but not to destroy their vitality entirely. A temperature of 60 °C. for 
5 minutes was not sufficient to attenuate the tubercle baccillus while 
the same temperature or 140 °F. for a period of 20 minutes destroys 
the tubercle bacillus absolutely without injuring the creaming or other 
properties of the milk. 



165 

In the extensive experiments of Rogers on the bacteria in pasteurized 
milk it was found that milji pasteurized in a continuous machine at 
a temperature of 185 °F. showed a reduction in bacterial content from 
10,000,000 to 500 per cubic centimeter. After 12 hours the pepton- 
izing bacteria in some samples of the pasteurized milk multiplied 
rapidly and the milk was usually curdled within 48 hours with the 
development of a disagreeable flavor and odor. In a few samples 
the lactic-acid bacteria resisted pasteurization and multiplied so 
rapidly after 24 hours that the peptonizing bacteria were unable to 
develop further. In most cases the bacteria in the pasteurized milk 
developed so slowly that no change in flavor was noted until 96 hours 
alter pasteurization. 

It has to be recognized that pasteurization is only partly effective 
in destroying the bacteria in the milk and furthermore that it is im- 
possible to render milk absolutely sterile even by boiling for a long 
period. The boiling temperature will of course destroy all vegetative 
forms of bacteria but spore-bearing forms will resist this temperature 
and will develop later in the pasteurized milk. The greatest danger 
connected with pasteurized milk is the feeling of false security which 
it gives to the ordinary milk consumer. The idea seems to prevail 
quite generally that pasteurized milk is sterile and must be a perfectly 
safe food until consumed. This, however, is far from being the case. 
As already indicated, pasteurization is more likely to destroy the 
lactic-acid bacteria than the peptonizing bacteria. For this reason 
the peptonizing bacteria have a free field in which to develop after 
the milk has been pasteurized. The absence of lactic-acid bacteria 
prevents the development of an acid which would check the growth 
of peptonizing bacteria. The latter, however, are the micro-organisms 
which cause nearly all of the disgusting flavors or odors in milk and 
may produce dangerous toxins and other bacterial products. Pasteur- 
ized milk, therefore, should receive the same treatment after pasteur- 
ization as raw milk. In other words, it must be brought down as soon 
as possible to a temperature of 40 to 50 °F. and kept at that tempera- 
ture until used. Moreover, the exercise of care in preventing con- 
tamination of pasteurized milk is of more importance than in the case 
of raw milk. 

Effect on the Physical Properties of Milk. 

The pasteurization of milk has the effect of diminishing its viscosity 
for the reason that the fat globules, which in normal milk have a 
tendency to occur in irregular clumps are distributed more uniformly 
after pasteurization. If milk contains calcium chlorid the coagulation 
point of the casein is reduced as a result of pasteurization, but the 
time required for coagulation is lengthened. The effect of pasteuriza- 
tion upon the fat globules and upon the cleanness of skimming has 
been found to vary considerably depending upon the conditions of 
pasteurization. If milk is put under considerable pressure in the 



166 

pasteurizer the loss of fat in the skimmed milk in running through a 
separator is greater than when no pressure -was used in the pasteurizer. 
The slight coagulation of casein which may occur in heating milk is 
apparently due to a change in the structure of the casein combined 
with the action of small amounts of acid formed from lactose when 
milk is heated at high temperatures. 

Since the relative consistency or viscosity of cream is somewhat 
affected by pasteurization a number of experiments have been made, 
particularly by Babcock and Russell for the purpose of restoring the 
consistency of pasteurized cream. It was found that the viscosity of 
pasteurized cream could be restored by adding freshly slaked lime in 
solution. The lime solution was prepared in a solution of cane sugar 
in water. No sanitary objection can be raised to this process since 
lime is a normal constituent of milk and the amount added for re- 
storing viscosity rarely exceeds four parts per 10,000. Finely divided 
e,gg albumen, tricalcium prosphate and blood fibrin were tested for 
the same purpose with poor results. It was found, however, that one 
part of rennet per 200,000 parts of pasteurized cream was sufficient 
to restore the consistency of the cream within a few hours. 

It has been found that milk heated too long or at a too high tem- 
perature will not afterward coagulate under the action of rennet. In 
general the completeness of coagualtion is somewhat hindered by 
pasteurization. If milk is pasteurized after a slight acidity has 
already developed, for example 0.2 per cent, there is danger of the 
milk coagulating during the process of pasteurization. There seems 
to be little objection which can be raised to pasteurization from the 
standpoint of butter making since butter from pasteurized milk 
ordinarily scores as high as that from unpasteurized milk under the 
same conditions. 

Effect on the Chemical Properties of Milk. 

In experiments by Rettger it was found that sulphid was given off 
when milk was heated to a temperature of 85 °C. This was apparently 
hydrogen sulphid due to the partial decomposition of the milk proteids. 
The amount of sulphid thus liberated is very small but is sufficient to 
be detected by lead acetate or potassium permanganate. The extent 
to which the proteins of milk are affected in their essential composition 
is not sufficiently understood. A number of investigators have found 
that the lecithin content of milk is considerably reduced by pasteuriza- 
tion. In nearly all cases the acidity of milk is also diminished by 
heating. 

Effect on Digestibility. 

The literature relating to the digestibility of pasteurized milk is 
very extensive. For the most part it relates to the use of pasteurized 
milk for the use of children and to the supposed harmful results of 
using pasteurized milk continuously. The extensive literature on 
this subject, however, is open to the objection that the care of the 



167 

milk after pasteurization was not taken into consideration. In the 
few careful experiments which have been made with calves, dogs, 
and children, it appears that no injurious changes have been definitely 
'shown to take place in milk as a result of pasteurization. 

The advantages and disadvantages of pasteurization have been well 
summed up by Rosenau. In the first place, it has been claimed that 
pasteurization promotes carelessness on the farm and dairy. The idea 
underlying this objection is that if the dairyman knows that his milk 
will be pasteurized after reaching the city or in a central pasteurizing 
pi ant, he is less likely to use the necessary precautions regarding the 
sanitary handling of his milk. This possible objection may be over- 
come by suitable inspection of dairy premises and the enforcement of 
sanitary regulations upon these premises. If the larger part 
of the milk supplied to cities is to be pasteurized it is of 
great importance that all contamination after the milk has been drawn 
should be reduced to a minimum in order to avoid the entrance of 
spore-bearing peptonizing bacteria into the milk. The objection that 
pasteurized milk is less digestible than raw milk is not well founded 
since there are no reliable experiments indicating that the digestibility 
of milk is affected by pasteurization. The claim that pasteurized 
milk causes scurvy or serious digestive disturbances is in most cases 
based on careless observation of cases in which the milk after pasteur- 
ization was allowed to become contaminated or was not kept at a 
sufficiently low temperature to prevent the development of peptonizing 
bacteria. The most serious objection to pasteurization is that it 
destroys the lactic-acid bacteria which are the only safeguard against 
the development of more harmful species of bacteria in milk. The 
only means of preventing this unfavorable result is to keep pasteurized 
milk at a low temperature. The campaign of education along this 
line is absolutely necessary in order to prevent milk consumers from 
entertaining the comfortable assurance that pasteurized milk can not 
pussess harmful properties. It is quite true that pasteurization does 
not render milk completely sterile but there is no known method of 
accomplishing this result except that of repeated boiling corresponding 
to the method of fractional sterilization of nutrient media in bacterio- 
logical research. This is obviously an impossible procedure for adop- 
tion on a commercial scale since it would be very expensive and the 
flavor of the milk would be greatly altered. The objection that pas- 
teurization increases the cost of milk is of very little weight since it 
is certainly a cheaper method of rendering milk safe than any other 
which has yet been devised. It must be recognized by milk consumers 
that the production of safe and sanitary milk answering the require- 
ments of municipal health officers is accompanied with more expense 
than was necessary for the production of market milk ten years ago. 
In order that milk producers may take a more lively interest in the 
production of strictly sanitary milk it is first necessary that the 
consumer should recognize that there are different grades of milk 



168 

varying in cleanness and wholesomeness and consequently varying in 
their real value. So long as consumers are not willing to pay some- 
what more for clean, healthy, and wholesome milk than for ordinary 
unguaranteed milk the producer can not be expected to devote his time 
and energy to scuring a superior article which must compete with 
an inferior grade of milk on the market for the same price. 

In order to overcome the objections which in many cases have been 
found to hold against pasteurized milk it seems most desirable, as 
has already been suggested by various sanitary officers, that a central 
pasteurizing plant, preferably under private management, be estab- 
lished in every city where all milk which can not be otherwise certified 
shall be pasteurized before being placed on the market. 

Pasteurization by means of electricity is discussed in connection 
with the bacteriology of milk. 



169 



CHAPTER X. 

PRESERVATIVES IN MARKET MILK. 

The action of chemical preservatives in hindering the development 
of bacteria and preventing decomposition of food products has long 
been a matter of common knowledge. A list of preservatives which 
have been used in attempts to improve the keeping properties of market 
milk is, however, not very large. It includes formaldehyde, boric acid, 
borax, hydrogen peroxid, benzoates, salicylates, sodium carbonate, 
saltpeter, chromates, etc. In recent years, however, nearly all of 
these preservatives except formaldehyde have been discarded as far as 
milk is concerned. The general question of the use of preservatives 
in food products is at present prominently before the people and the 
effects of these preservatives are being carefully studied in order to 
secure a solid scientific basis for rulings under the new food and drug 
legislation. Without admitting that the. use of preservatives is harm- 
less or justified in the case of any food it is particularly objectionable 
in the case of milk for the reason that this product may be obtained 
strictly fresh twice daily and may be delivered to the customer in a 
perfectlv fresh and wholesome condition even from a distance of 300 
to 400 miles by the simple observance of rules of cleanliness and the 
use of refrigeration. Clean milk kept cool will not sour or undergo 
other harmful changes within the period of time in which it may 
reasonably be kept in the household before using. 

It may be stated in advance of the special discussions to be given to 
different preservatives that as yet we know no chemical substance 
which is at the same time germicidal and without harmful effects on 
the living cells of the body. It is well also to bear this undoubted fact 
in mind considering the possible use. of proprietary preservatives, for 
almost without exception these preservatives contain the usual chemical 
substances which are known as preserving agents. Although being sold 
under trade names they are nevertheless no more harmless than sali- 
cylic acid, borax, formaldehyde, and the other materials of which 
they are composed when used in a pure state. In fact, there are more 
serious objections against proprietary preservatives than against pure 
chemical preservatives for the reason that their composition is more 
variable and excessive doses of one or the other of their constituents 
may, therefore, be taken in drinking milk. 

Formaldehyde. 

Formaldehyde is an oxidation product of methyl alcohol and bears 
the chemical formula H. COH. The commercial formalin or formol 
is a 40-per cent solution of formaldehyde gas in water. Formaldehyde 
has been used as a disinfectant and germicide for about 20 years. 



170 

In surgical operations it has not given the satisfaction that was at 
first expected from it on account of its irritating effect upon the 
tissues. Its use as a preservative of foods began about 1895. It is 
now extensively used in the preservation of milk. 

Milk containing 1 part of formalin to 5,000 parts was found by 
Merkel to keep sweet for 100 hours at a temperature of 25 °C. and for 
50 hours when containing 1 part of formalin in 10,000 parts. The 
same investigator noted that some of the casein was precipitated in 
Hakes and that the presence of formalin interfered with the digestion 
of the milk proteids. Similarly Rideal found that milk containing 
formalin at the rate of 1 part in 10,000 would remain fresh for 7 
da vs. On examinine; market milk this author found that one-half 
pint of formalin had been used in the preservation of 17 to 18 gal. 
of milk. ]STo artificial flavor or smell appeared in milk treated with 
formalin even after it had been boiled. Young found, as a result of 
an examination of all available literature on the subject of formalde- 
hyde, that when this substance is used as a preservative it tends to 
lower the nutritive value of milk and to interfere with the digestive 
processes. In the proportion of 1 :1,000, formaldehyde exercises a 
decided germicidal action. Its germicidal effect is even noticeable 
when used in milk at the rate of 1 to 100,000. Rivas claims that 
when used in the proportion of 1:50,000, formaldehyde disappears 
from milk within 24 to 72 hours and that it begins to disappear within 
t> hours. If formaldehyde is added to milk in higher proportions the 
disappearance of the preservative is very slow. 

The direct effect of formaldehyde upon animal tissues is to cause 
a considerable hardening as a result of the extraction of water. In a 
series of experiments by Rideal and Fullerton on kittens, rabbits, and 
guinea pigs, it was found that formaldehyde in the quantities ordi- 
narily used in the preservation of milk had no striking effect upon 
proteid metabolism as shown by the weight of the animals. In these 
experiments formaldehyde was used at the rate of 1 part in 50,000. 

The proteids of milk are undoubtedly changed by means of the 
presence of formalin and relatively large quantities of formalin are 
necessary to prevent harmful changes taking place in market milk. 
The antiseptic power 1 of formaldehyde, however, is considerably 
greater than that of boric acid, in fact 50 times greater according 
to the investigations of Cochran. This writer found that milk treated 
with formaldehyde at the rate of 1 part to 10,000 underwent artificial 
digestion in about the same time and manner as milk untreated. 
Even small amounts of formaldehyde, however, lessen the coagulability 
of casein with rennet and interfere with the natural digestion of 
casein. In experiments by Trillat it was found that the digestibility 
of untreated casein was from 5 to 30 per cent greater than that of 
milk treated with formaldehyde in varying amounts. From these ex- 
periments it was concluded that formaldehyde is harmful or even 
dangerous for infants. 



171 

The experiments of Price with formaldehyde and milk in vitro 
indicated that this preservative when used at the rate of 1 to 20,000 
will keep milk fresh for 40 hours. Even when used to the extent of 1 to 
2,500 parts the formaldehyde appeared to have no effect on the activity 
of fresh enzyms, rennet, pepsin, or other digestive ferments. Price 
concludes, therefore, that formaldehyde may be added to milk in 
sufficient quantities to preserve the milk and prevent the development 
of some of the bacteria without having any deleterious effects on 
the digestibility of the milk in vitro under artificial conditions. These 
conclusions can not be accepted as applying to natural digestion in 
the stomach especially in view of the almost unanimous findings of 
physiologists against the use of formaldehyde in milk or other food 
products. 

In recent years, von Behring has at various times recommended 
the use of formalin in the preservation of the milk of cows which had 
been rendered immune to tuberculosis or which may be suspected of 
excreting tubercle bacilli with their milk. The idea underlying this 
recommendation of von Behring is that formalin when used in the 
proportion of 1 part to 10,000 of milk will destroy the tubercle bacilli 
which may be present in milk without affecting the immunizing bodies 
which may also occur in the milk. In this way it was suggested that 
milk might have a slight immunizing effect toward tuberculosis. No 
confirmation of this view has been obtained and the matter seems to 
have little practical importance. 

Boric Acid and Bokax. 

The two boron compounds most frequently used in attempts to pre- 
serve milk are boric acid ( H 3 B0 3 ) and borax or sodium borate 
(Na s B 4 Ov +H 3 O). The free boric acid is obtained by decomposing 
borax in aqueous solution in strong HC1. Borax is obtained in 
enormous quantities in Death Valley and elsewhere. 

According to the experiments of Buchholtz it is necessary to use a 
6-per cent solution of borax or boric acid in order to prevent the 
growth of molds in sugar solutions. It has also been found that typhoid 
bacilli will grow in a 1 per cent solution of boric acid. 
Kitasato recommends that boric acid should be stricken from the list 
of disinfectants. Experiments by Koch showed that anthrax bacilli 
remain alive for 100 days in a 2-per cent solution of boric acid and 
that even a 5-per cent solution of borax for 10 days showed little effect 
upon the growth of anthrax bacilli. It is quite apparent that borax 
has a weak germicidal effect and must, therefore, be used in large 
quantities in order to destroy pathogenic bacteria which may be found 
in milk. With regard to the effect of borax upon the spontaneous 
coagulation of milk, Lange found that in the case of milk which would 
naturally coagulate in 2% days, 1 per cent of boric acid prevented 
coagulation for 7 days and 2 per cent prevented coagulation for an 
indefinite time. In other experiments the development of lactic-acid 



172 

bacteria has been very materially checked in fresh milk by the addition 
of 0.25 to 0.5 per cent of boric acid. On the other hand Reenter 
found that even 4 per cent of borax did not prevent the growth of 
liquefying and putrefactive bacteria but did check the development 
of lactic-acid bacteria. 

If boric acid is added to milk, the latter acquires a liquefying 
property in the presence of a high percentage of lactic acid and bitter- 
ness may be observed in milk treated with borax or boric acid. Most 
of the borax added to fresh milk may be removed by running the milk 
through a separator, and boric acid added to cream is largely removed 
in the buttermilk and washing water. The action of rennet is invar- 
iablv hindered by the use of borax. 

As to the effect of borax upon human beings and experimental 
animals only the briefest summary of the literature need be made 
here since it is too extensive to be referred to in detail. In feeding 
experiments it has been found that 0.2 gm. of boric acid is poisonous 
to guinea pigs. The nitrogen metabolism of dogs is not always 
affected by feeding them daily doses of 3 gm. of boric acid. Boric 
acid has been used in the treatment of epilepsy and certain other dis- 
eases and when thus administered in doses of 2 to 3 gm. daily for 
several months, it almost invariably causes skin eruptions. In fact its 
use even for short periods may result in a drying of the skin and 
exanthema or papules in which some of the boric acid is excreted. 
Kister found that daily doses of 1 gm. of boric acid or less caused 
diarrhea, nausea, albuminuria, and loss of weight. The irritating 
effect of boric acid may be quite pronounced when used as a mouth 
wash. In some individuals the mucous membrane is eroded by the 
use of a 4-per cent solution of boric acid. In some cases a persistent 
inflammation of the mucous membrane of the mouth has been brought 
about by the use of a wash of boric acid. In rabbits, guinea pigs, and 
other experimental animals the internal use of boric acid has caused 
diarrhea, weakness, and subnormal temperature. An irritation of 
the digestive tract, gastric pain, and diarrhea have been reported from 
tiie administration of a single dose of 2gm. of boric acid. Cats also 
appear to be susceptible to borax and may be readily killed by repeated 
doses of this substance. In the experiments reported by Liebreich, 
rabbits and dogs appeared to endure the continued administration of 
borax or boric acid without noticeably harmful results. 

The most extensive experiments to determine the effect of boric acid 
and borax upon man have been carried out by Wiley and his assist- 
ants. These expriments, as is generally well known, were made on 
voluntary subjects who were previously determined to be in normal 
health. In these experiments it was found that both boric acid and 
borax taken into the stomach were largely excreted by the kidneys at 
least to the extent of 80 per cent. In the whole series of experiments 
a marked tendency was noted to lose in body weight, The preserva- 
tives appeared to have no effect upon the number of the blood cor- 



173 

puscles but gave a strongly alkaline reaction to the urine and increased 
its content of albumin. The quantity of phosphoric acid excreted was 
also larger than is normally the case. 

Wiley concludes from his experiments that it is unsafe to use borax 
or boric acid even in the minutest doses in any food product. This 
ground seems justifiable for the reason that it is impossible for any 
individual to determine how much borax he is eating daily, if this 
preservative is used in a great variety of foods. The individual is, 
therefore, not in a position to limit the daily dose of borax so long as 
it is used in the preparation of these foods. The continued use of 
boric acid to the extent of 4 or 5gm. per day produced a loss of appe- 
tite, inability to work and decided illness. In many cases the same 
results were produced from the use of 3 gm. per day or exceptionally 
even from 1 gm. "It appears, therefore, that both boric acid and 
borax when continuously administered in small doses for a long period 
or when given in large quantities for a short period create disturbances 
of appetite, of digestion, and of health." 

Hydrogen Peroxid. 

This antiseptic depends largely for its germicidal and physiological 
action upon its powerful oxidizing property. As is apparent from 
its formula (H2O2 ) it may be readily made to yield up some of its 
oxygen which combines with other substances producing a rapid 
oxidization. Peroxid of hydrogen is a powerful oxidizer of animal 
tissues, starch, and sugar. It has been somewhat used in medicine 
m the treatment of fevers and whooping cough but in this regard its 
use is declining. As an antiseptic, particularly for suppurating ulcers 
and sores its finds great favor. When used at the rate of 1 :100 it is 
an energetic disinfectant. At the rate of 1 :352 it kills anthrax spores 
within a few days but at the rate of 1 :1,000 its antiseptic power is 
weak. Peroxid of hydrogen has been used as a mouth and nose wash 
in cases of scarlet fever, diphtheria, and similar diseases. As ordi- 
narily understood it is usually free from poisonous properties and 
on account of the fact that it is so easily decomposed there is less 
objection to the use of hydrogen peroxid in milk than to any other 
preservative which has been suggested. Commercial peroxid of hydro- 
gen contains 3 per cent of pure H 3 O s in solution in water. In a 
pure state H2O2 begins to give up some of its oxygen at 60 °F. but in 
water this does not take place below a temperature of 100°F. In milk 
peroxid of hydrogen is readily decomposed giving up some of its 
oxygen in oxidizing milk sugar. Under ordinary conditions it is 
probable that hydrogen peroxid is entirely removed by the pasteuriza- 
tion of milk. 

In experiments by Huwart it was found that the pasteurization of 
milk immediately after the addition of hydrogen peroxid removed 
about two-thirds of this antiseptic and that pasteurization at the end 
of 18 hours removed every trace of it. Gonnet, for a period of two 



174 

months, drank y 2 liter of milk daily containing 8 per cent of hydrogen 
peroxid and without experiencing the least harmful effects. At the 
same time it was found that 1 cc. of hydrogen peroxid would preserve 
1 liter of milk for 2 days. A number Of French investigators have 
recommended the use of H 2 2 in milk as entirely unobjectionable 
provided the solution contains no free acid. In experiments by Chick 
it appeared that the addition of 0.2 per cent H 2 2W as sufficient for 
the complete sterilization of milk and that .1 per cent sufficed to keep 
the milk sweet for a week or longer. The milk acquired a striking 
flavor, however, which was noticeable even when the H 2 2 was used at 
rate of 1 part to 10,000. Chick, therefore, recommends that H 2 O s 
be used in the preservation of samples but not in market milk. 

While hydrogen peroxid in a fresh state is a vigorous antiseptic, it 
decomposes so rapidly under the influence of heat or in the presence 
of organic compounds that its antiseptic value in a compound like 
milk is not very great. In milk it does not destroy pathogenic bacteria. 
It has been found, however, that the number of bacteria in dry milk 
preparations is reduced by treating the milk with Hs () 2 before 
desiccation. 

The use of hydrogen peroxid in milk has been so thoroughly tested 
and recommended by Budde that the method has acquired the name 
Buddeizing and is often referred to under that name. The method 
as proposed by Budde depends on the action of nascent oxygen on the 
micro-organisms in milk at a temperature above 40 °C. Hydrogen 
peroxid is added to milk at the rate of 0.9 gm. per liter after which 
the milk is rapidly heated to 50°C. It is stated that the excess of 
hydrogen peroxid may be rendered innocuous by the addition of a 
sterile infusion of common yeast. Renard has reported a number of 
observations on the rate of decomposition of hydrogen peroxid in 
milk. It appears that a 2-per cent solution in milk was completely 
decomposed in from 6 to 8 hours. 

While hydrogen peroxid is free from the objections of positive 
harmfulness which clings to other preservatives it has not always 
been found to be a satisfactory antiseptic for destroying bacteria in 
milk and often gives a disagreeable flavor to the milk. Its effective- 
ness as a milk preservative is, therefore, so slight that no relaxation 
can be allowed in the observation of the rules for cleanliness and the 
application of cold. For this reason it appears undesirable to recom- 
mend or even permit its use in milk. 

Other Preservatives. 

Sodium Carbonate. — Sodium carbonate and other alkalis can 
scarcely be considered as preservatives. They are used merely for 
tne purpose of neutralizing the acidity of milk. The use of such 
substances can not be too highly condemned for the reason that the 
only purposes of adding them is to prevent the detection of the 
abnormal souring of milk which has already taken place. 



175 

Benzoic acid is obtained from benzoin by sublimation or is prepared 
artificially. The most common salt of this acid which has been used 
as a preservative in milk and other foods is sodium benzoate. This 
salt is more effective as a germicide than boric acid but is open to the 
objection of producing undesirable effects in man. 

Chromates are rarely if ever used in this country in the preservation 
of milk but in Europe they have occasionally been found associated 
with formaldehyde sometimes to the extent of 1 part in 1,000. 

Saccharin has a very weak antiseptic action and is of little or no 
value in destroying bacteria in milk. Moreover in repeated doses of 
Vt g m -> it causes harmful physiological results. 

Salicylic acid and its salts are quite often used in the treatment of 
rheumatism and gout. Extensive experiments under the direction of 
Wiley have shown that the popular belief that salicylic acid is the 
most injurious of all the preservatives is not well founded. It is 
harmful but not more so than other preservatives which have been 
used in milk and other food products. The general effect of salicylic 
acid and its salts is at first to stimulate the digestive organs to greater 
efforts and to increase the solubility and absorption of foods. The 
after effects, however, are depressing, the tissues are broken down more 
rapidly than they are built up and the metabolic processes are inter- 
fered with. The use of salicylic acid and its salts has a tendency to 
diminish the weight of the body, to produce symptoms of weakness or 
positive illness, to place an additional burden upon the kidneys, and 
to act as a depressant upon digestion and the general health. The 
results obtained by Wiley and his assistants in the study of salicylic 
acid have been largely confirmed by Leffman and other investigators. 

Fluorids. — Eluorids are little used as either milk or butter preserva- 
tives in this country. In France and other parts of Europe their use 
is reported from time to time. The presence of sodium or ammonium 
fluorids in butter to the extent of 0.01 per cent prevents the action of 
ptyalin and pepsin and, to some extent, that of diastase. Milk may 
be kept sweet for 2 or 3 days by the use of 0.2 gm. per liter of sodium 
fluorid but the harmful effects of fluorids should be sufficient reason 
for prohibiting their use. 

Potassium permanganate has occasionally been used in the preser- 
vation of milk samples but is inferior to potassium bichromate for 
this purpose. 

Potassium chromate is now and then added to milk at the rate of 
0.2 gm. per liter in order to give it a yellow color. Among the other 
preservatives which have in rare instances been used in milk, mention 
may be made of sulphites and copper sulphate. Milk treated with 
copper sulphate becomes slimy with long standing instead of curdling. 
The antiseptic action of copper sulphate appears to' be very slight. 



176 

Proprietary Preservatives. — As already mentioned the proprietary 
preservatives which have been placed upon the market with various 
guarantees concerning their harmless properties and efficient action 
have all been found upon examination to be composed of the well- 
known chemical substances which have been discussed in the above 
list of preservatives. It is not necesssary, therefore, to discuss this 
matter any further. 

General Conclusions on the Use of Preservatives in Milk. 

The recent decision of officials entrusted with the examination of 
the effects of preservatives, and of other chemists and sanitarians 
throughout the world have established beyond question the fact that it 
is impossible to use chemical preservatives which will prevent the 
decomposition of food products and destroy pathogenic or other bac- 
teria without exercising an injurious effect upon the digestive and 
other organs of the body. It seems impossible, therefore, to draw 
any other conclusion regarding the use of preservatives in milk than 
that they are unnecessary, undesirable, and positively injurious. They 
are unnecessary for the reason that milk will keep sweet a sufficient 
length of time if it is clean and cool. Preservatives in milk are 
undesirable for the reason that thev surest relaxation in general 
sanitation about the dairy. There can be little question that their use 
in the hands of the unscrupulous promotes carelessness and filthiness 
in the stable and in the handling of the milk. The preservatives 
which have thus far been used or suggested for use in milk do not 
possess an antiseptic power sufficient to destroy pathogenic bacteria 
in the dilution in which they must be used in milk in order not to be 
poisonous. Since, therefore, pathogenic bacteria can not be safely 
destroyed in milk by the use of chemical preservatives, these sub- 
stances constitute an added source of danger in that certain individuals 
are disposed to rely upon them for destroying disease germs, which 
they do not, and for the further reason that they are in themselves 
injurious to health. 



177 



CHAPTER XI. 

PHYSICAL AND CHEMICAL EXAMINATION OF MILK. 

The physical and chemical methods which have been proposed for 
determining the composition, adulteration, coloring or other artificial 
treatment of milk are too numerous and some of them are too restricted 
in their use to make a general discussion of all these methods desir- 
able in the present chapter. A description will be given of the prin- 
cipal methods which find favor in present practice in this country, and 
a briefer mention will be made of some of the other methods. 

Testing Cows foe Dairy Purposes. 

The farmers who test their own cows and keep a record of their 
fat and milk yield are in position to appreciate the necessity of testing 
market milk. Every dairyman should keep a record of the perform- 
ance of each of his cows. In this way he will know which cows are 
very profitable and which ones lower the profits from his dairy as a 
whole. Cows of similar appearance and conformation may differ 
greatly in their milk yield and fat production. In applying tests to 
dairies throughout the country it has been found that in almost every 
dairy there are cows which do not give enough butter fat to pay for 
their keep, while there are others in the same dairy which produce 
three or four times as much butter. It pays the dairyman therefore 
to know what each cow is doing. After having applied the test he 
can dispose of all cows which yield less than 200 pounds of butter 
per year. 

It is a very easy matter to test cows. Milk scales can be obtained 
from all dealers in dairy supplies, and it takes but a. moment to weigh 
the milk at each milking. If this be done the total yield of each cow 
will be known. Even if every milking is not weighed, the milk should 
be weighed two days of each week. It is not necessary to make a daily 
test for fat in each cow's milk. In determining whether a cow is good 
enough to buy or not a fairly correct idea of her fat production can 
be obtained from two tests. The first should be made about 6-10 weeks 
after calving, and the second after six or seven months. The dairyman 
will find it desirable to make a fat test of all cows in his herd every 
two weeks or at longest every month. Each test should be made upon 
a composite sample of milk made up of small samples taken each 
morning and evening for four days in succession. A test from a 
sample taken at one time is never representative. The fat content 
of the milk varies too greatly from day to day. A good average 
sample is obtained, by mixing samples from four days' milkings. 
When a sample is to be taken the cow should be thoroughly milked and 
the milk well mixed before sampling. Milking a few streams directly 



178 

into a sample bottle will never give an average sample, for the fat 
content increases from the beginning to the end of the milking. The 
samples must be kept in tightly stoppered bottles and the other direc- 
tion followed as usually recommended for making the Babcock test 
and as is described below. 

By means of the Babcock tester the farmer may not only determine 
the relative value of his cows, but he may also test the cream obtained 
by the gravity or centrifugal methods. A test may also be made of 
the skim milk and the efficiency of separation thus determined. An 
examination of the buttermilk will show whether churning is done 
under proper conditions. 

Examination of Market Milk. 

Naturally the milk inspector in the examination of market milk 
will limit his operations to the points specified in the law from which 
he derives his authority. Municipal milk inspection regulations are 
too often inadequate to protect the health of the milk consumer. The 
mere removal of a part of the cream from milk does not render the 
milk harmful although it is a palpable fraud. On the other hand the 
presence of peptonizing or pathogenic bacteria is a menace to health. 
Removal of cream from market milk is a deliberate perpetration of 
a fraud, the use of preservatives is an attempt to cover up the evidence 
of careless or insanitary handling of milk, but the presence of patho- 
genic bacteria is due to an unconscious, or in some cases an almost 
criminal carelessness. 

In some towns the inspector merely determines whether the fat 
percentage is up to the standard. In others he tests for fat and total 
solids. In still others attention is given also to specific gravity, tem- 
perature, dirt, bacteria etc. A complete examination of market milk 
should take cognizance of specific gravity, temperature at time of 
delivery, fat, total solids, pasteurization, contamination with dirt and 
bacteria, acidity, flavor, odor, color, and addition of preservatives, 
adulterants and coloring matters. The methods of taking samples 
of milk for examination, of determining specific gravity, fat, total 
solids, proteids, sugar, ash and acidity, and of detecting preservatives, 
adulterations and coloring matters are discussed in the following 
sections of this chapter. The methods are those which have been 
adopted by the Association of Official Agricultural Chemists, or are 
recommended by Richmond, Van Slyke, Farrington and Woll, Web- 
ster, Hills and other investigators. 

Taking, Preserving- and Caring for Samples. 

It is of the greatest importance that each sample of milk taken for 
analysis or examination should represent the true average composi- 
tion of the milk to be tested. If the constituents of the milk are not 
thoroughly mixed in their normal proportions before the sample is 
taken, the results obtained from the test of the sample will be of no 



179 

value, but rather misleading. Several precautions are therefore 
strictly to be observed in sampling milk. If the milk is perfectly 
fresh and no appreciable rising or clumping of the cream has taken 
place a thorough mixing will insure an average composition to the 
sample. At creameries the milk is sufficiently mixed by pouring 
into the weigh can. Otherwise it may be poured from one can to 
another, or mixed by stirring. Too violent stirring should be avoided 
since a partial churning may result, making it more difficult to get 
a representative sample. If a distinct layer of cream has risen to 
the surface the mixing must be continued longer but must be gentle. 
Milk containing dried or hardened cream is to be heated for 5-10 
minutes to a temperature of 105-110°F., or until the clumps of 
cream are melted. It is then stirred and. sampled. 

Milk transported in partly filled cans and violently agitated may be 
partly churned when examined by the inspector. In such cases also 
it should be warmed till the cream melts after which it is mixed by 
pouring or gentle stirring and sampled. In all cases samples may be 
taken with a half-ounce milk dipper or with a sampling tube. Ether 
may be used in the place of heat to dissolve clumps of cream. If 5 
per cent of ether be shaken with the milk till the cream is dissolved, 
and the mixture again shaken vigorously to redistribute the cream a 
representative sample may be obtained. After such treatment the 
fat reading should be increased by 5 per cent as a correction for the 
added ether. 

In sampling coagulated milk Van Slyke recommends that 5-10 
per cent of strong soda or potash lye or ammonia water be added to 
dissolve the casein. The milk is shaken till it becomes liquid after 
which it is immediately sampled. In testing milk treated in this 
manner the sulphuric acid must be poured in slowly since a high 
degree of heat is developed. 

In freezing, the constituents of milk become very unevenly dis- 
tributed. The cream is largely caught in the ice at the surface. Other 
frozen portions are poor in solids, while the liquid portion is rich in 
solids. Frozen milk must be melted by heat and thoroughly mixed 
before sampling. 

A composite sample is a mixed sample taken day after day from 
the same source. Thus a composite sample from a single cow con- 
tains portions of the morning and evening milkings of two or more 
days in succession. Composite samples in creamery work are made 
up in the same manner from the milk delivered day after day by the 
same patron. The daily samples are allowed to accumulate in a jar 
or bottle for one or two weeks. The jar or bottle should be tightly 
stoppered so as to prevent all evaporation. In order to keep a com- 
posite sample in condition for testing it is necessary to use some kind 
of preservative. For this purpose bichromate of potash, formalin 
and corrosive sublimate are most used. 

A choice of preservatives will depend somewhat on experience. 



180 

Farrington and Woll prefer bichromate of potash on the grounds of 
harmlessness, cheapness and efficiency. One half gram will preserve 
a pint of milk for one or two weeks. At first the milk is colored red 
but later the color becomes lighter. As shown by Van Slyke hot 
weather may make it necessary to use more bichromate of potash, 
and lactic acid interferes somewhat with its efficiency. It is always 
best to keep composite samples in a dark, cool place. 

One cc. of formalin will keep a pint of milk in good condition for 
bhe required time. The excessive use of either formalin or corrosive 
sublimate will harden the casein so that it is less readily dissolved by 
the sulphuric acid in testing. 

Corrosive sublimate is a powerful antiseptic but is very poisonous 
and the milk does not indicate its presence. Tablets of corrosive 
sublimate containing a coloring matter to denaturize the milk are put 
up specially for this purpose. Penny has tested a large number of 
other preservatives for milk samples, including hydrogen peroxide, 
bromine, iodine, caustic potash, ammonia, potassium carbonate, am- 
monium carbonate, magnesia, sodium chloride, barium chloride, 
ammonium chloride, calcium chloride, stannous chloride, potassium 
iodide, nitrate of sodium, potassium, magnesium, ammonium, stran- 
tium, silver and lead, potassium sulphate, potash alum, sulphate of 
magnesium and zinc, sodium thiosulphate, potassium chlorate, am- 
monium sulphide, potassium sulphocyanate, potassium ferrocyanide, 
potassium permanganate, chromic acid, boric acid, formate of am- 
monium and calcium, lead acetate, ammonium oxalate, alcohol, ether, 
glycerine, benzene, salicylic, carbolic and tannic acids, oil of pepper- 
mint, oil of cloves, camphor, quinine, tobacco, etc. There seems, how- 
ever, to be little reason to use any preservative other than bichromate 
of potash, formalin or corrosive sublimate. Penny has experimented 
with the method of submergence in preserving milk samples. This 
consists in using a solvent heavier than milk to dissolve the fat and 
carry it to the bottom of the sample where it is preserved in a better 
physical condition than when it rises to the surface. The chief sol- 
vents used for this purpose were ethyl bromide, carbon bisulphide and 
chloroform. These solvents are too expensive for practical use and 
must be driven out of the milk before the test is made. This may 
be done by adding acetic acid and boiling. 

Whether formalin, corrosive sublimate, or bichromate of potash is 
chosen the entire amount should be added to the first lot of milk 
placed in the sample jar. The preservative must be mixed with the 
milk by slowly rolling the jar. Every time a new lot of milk is added 
the whole should be thoroughly mixed. In the intervals the jars 
may be gently shaken to prevent the formation of a tough layer of 
cream on the surface. 

Sampling cream. — In sampling cream the same precautions are to 
be observed as with milk. The fat in cream has a tendency to rise 
to the surface as in milk. It is more necessary to melt cream than is 



181 

usually the case with milk in order to get a correct sample. Hills 
recommends that the composite sample of cream be heated to 105- 
110 °F. before the amount to be tested is removed. Hills also devised 
a cream sampling sieve through which the cream is passed in order 
to break up the clumps. 

Determination of Specific Gravity. 

The determination of the specific gravity of milk is of importance 
because when once known together with the fat percentage the amount 
of solids not fat may be calculated by formulas worked out by Bab- 
cock and others. If a vat which will contain exactly 1000 pounds of 
water is filled with milk the latter will weigh about 1032 pounds. 
The average specific gravity of milk is therefore said to be 1.032. The 
casein, albumin and sugar of milk are heavier than water while the 
fat is lighter. If fat is removed from milk its specific gravity is 
raised while by the addition of water it is lowered. It is possible 
therefore to remove some of the fat and then add enough water to 
make the specific gravity that of normal milk. It is thus impossible 
always to detect defective milk by its specific gravity. The determina- 
tion of specific gravity, however, is of value in detecting highly ab- 
normal milks. 

The instrument most frequently used for this purpose is the lacto- 
meter of which there are two in common use in this country, the 
Quevenne and that of the New York Board of Health. The lacto- 
meter is a hygrometer specially adapted for use in testing milk. The 
scale of the Quevenne lactometer is divided into 25 equal spaces, 
ranging from 15 to 10, and corresponding to the hygrometer readings 
1.015 to 1.040. Milk to be tested is supposed to be at a temperature 
of 60°F. A correction of .1 is to be added to each degree above 60°F. 
and the same subtracted for each degree below 60 °F. The lactometer 
is placed so that it floats freely in the milk. The point on the scale 
at the surface of the milk is then noted and also the temperature of 
the milk. Corrections are then made for temperatures above or below 
60°F. The milk should preferably be near 60°F. 

In the New York Board of Health lactometer the zero point is at 
the top of the scale which is divided into 120 equal spaces. The zero 
point indicates a specific gravity of 1.029, the lowest known for normal 
milk. One degree on the New York Board of Health lactometer 
equals .29 of a degree on the Quevenne. A New York Board of 
Health reading is converted into a Quevenne reading by multiplying 
by .29. A correction of .3 is made for temperatures above or below 
60 °F. Milk should be one or two hours old before testing and the 
lactometer should be scrupulously clean. 

Babcock's formulas for determining solids. If L be the Quevenne 
reading and f the fat percentage, then the solids not fat= 1 / 4L + .2f, 
and the total solids= 1 / 4Li-(-l-2f. These formulas give results which 
closely agree with those obtained with Richmond's slide rule, which 
is accompanied with directions for its use. 



182 

There are several other lactometers on the market but they are not 
so commonly used in this country. The lactometers of Soxhlet and 
Vieth both have a scale which reads from 25 to 35. Gralaine's lacto- 
meter is self correcting for the various temperatures of the milk. 
Richmond considers the thermolactometer and Soxhlet's and Vieth's 
as the best for testing milk. 

Pycnometer. — By the use of a pycnometer more accurate results 
are obtained than with a lactometer. As performed by Farrington 
and Woll the test is made as follows. A specific gravity bottle hold- 
ing 100 gm. of water is carefully cleaned, weighed on a chemical 
balance and filled with recently boiled water at a temperature slightly 
below 60 °F. The opening of the side tube is then wiped off and 
closed. The outside of the bottle is wiped dry and the bottle weighed. 
The same process is then gone through with milk. The weight of the 
empty bottle subtracted from that of the bottle filled with, water and 
with milk will give the weight of the water and milk respectively. 
The specific gravity of the milk is found by dividing the weight of the 
milk by that of the water. Fraudulent skimming is clearly indicated 
if the specific gravity is 1.040 or higher. 

Determination of Fat. 

The fat in milk may be estimated by the volumetric, gravity, densi- 
metric, areometric and other methods. The volumetric method is 
sufficiently exact for the control of market milk, and of the methods 
belonging to this class that of Babcock is almost universally used in 
this country. 

The Babcock test. — The great advantages of the Babcock test are 
its simplicity and ease of operation. The method depends simply 
upon centrifugal force and the action of sulphuric acid on milk 
serum. Sulphuric acid dissolves the milk proteids, reduces the vis- 
cosity of the milk and increases the specific gravity of the serum. 
The heat developed in the mixture of milk and acid causes the fat 
globules to coalesce. The centrifugal force brings about a rapid sep- 
aration of the fat and serum. Babcock testers may be operated by 
hand or by steam turbine action. The apparatus consists of test 
bottles, pipette for measuring milk, acid measure and centrifugal 
machine. In making a test exactly 17.6 cc. of milk is drawn into the 
pipette, it being estimated that .1 cc. will adhere to the pipette in 
emptying. This milk is poured into the test bottle, the latter being 
held on the slant so that the milk runs down one side. Exactly 17.5 
cc. of sulphuric acid of a specific gravity of 1.82 or 1.83 at 60 °F. is 
measured out in the acid measure, and poured down the slanting neck 
of the test bottle, being mixed with the milk by a rotary motion. The 
mixture is allowed to stand about five minutes and mixed again. The 
temperature of both the milk and acid should be between 60° and 
70 °F. The bottles are then placed in the tester and whirled for 4 or 
5 minutes at a speed of 600 to 1200 revolutions per minute according 



183 

to the diameter of the wheel. As stated by Harrington and Woll the 
necessary number of revolutions for a ten inch wheel is 1074 per 
minute, and for a 24 inch wheel 693 per minute. After the first whirl- 
ing add fairly hot water to bring the mixture up to the neck of the 
bottles and whirl for one minute. Again add hot water to bring the 
mixture up to the 8 or 9 per cent mark and whirl one minute. The 
per cent of fat may then be read while the temperature of the milk is 
about 130 °F. The lower surface of the column of fat is straight and 
offers no difficulty in reading. The upper reading should be taken 
at the point where the fat comes in contact with the neck of the 
bottle. Black specks in the column of fat may be due to too much 
acid, too strong acid or too high a temperature. White specks of 
undissolved casein in the fat may be due to too weak acid, too little 
acid or too low temperature. Foam on the fat column is usually due 
to the use of hard water. Only soft water should be used. All ap- 
T>aratus in this test should be calibrated before using. 

Gerbers acidobutyrometer. — This method is essentially a modifica- 
tion of that of Lefiman-Beam. Amyl alcohol is used in addition to 
sulphuric acid to hasten the separation of the fat. The method gives 
fairly good results. 

In a number of patented tests such as the sin-acid and Grerber's 
sal-test no acid is used. In the De Laval butyrometer only 2 cc. of 
milk is used and the rate of revolution is 5000 to 6000 per minute. 
In Fjord's centrifugal cream tester no chemicals are used, the milk 
being whirled for 20 minutes at a rate of 2000 revolutions per minute 
at a temperature of 131°F. The chemicals used in the Leifman-Beam 
method are sulphuric acid, and amyl alcohol mixed with hydrochloric 
acid. The advantage claimed for this method is that the necessary 
time of whirling is reduced. The Russian milk test is the regular 
Babcock test so modified that the bottles can be filled with hot water 
while being whirled. Bartlett modified the Babcock test by using 
20 cc. instead of IT. 5 cc. of acid and filling the bottles to the scale 
with hot water. The milk is whirled only once. The lactoscope is 
essentially a Fjord centrifugal cream test modified so as to be attached 
to a separator. It was devised by Berg and is considered fairly ac- 
curate. Among the other tests which have been published mention 
may be made of that of Willard, Parson, Cochran, Patrick, Lieber- 
mann, Schmid, Rose-Gottlieb, Thoerner, Demichel Lescoeur, Smith, 
Weiss and others. The milk inspector in this country, however, need 
apply no other volumetric test for fat than that of Babcock. 

The areometer test of SoxMet. — In this test 200 cc. of milk is run 
into the test bottle after which 10 cc. of potash solution is added (with 
a specific gravity of 1.26 or 1.27, and made by dissolving 400 gm. of 
caustic potash in one liter of water), and also 60 cc of ether. The 
bottle is first violently shaken and later gently shaken every half 
minute until a clear layer of dissolved fat rises to the surface. Enough 



184 

of the etherial solution is then blown up into the jacketed tube to 
float the areometer and the reading is made. 

The Adams method- — This is perhaps the best known of the Euro- 
pean gravimetric methods for estimating the fat of milk. The 
original method consisted in pipetting 5 cc. of milk into a beaker after 
which a roll of blotting paper was introduced and make to absorb 
the milk as completely as possible. The weight of the milk thus 
absorbed is determined, and the coil of blotting paper is dried to a 
constant weight in an oven at a. temperature of 100 °C. In this way 
the total solids as well as the fat may be determined. The dry coil 
of blotting paper is placed in a Soxhlet extractor. The total extract 
after the ether is evaporated is considered fat. Various modifications 
of this method have been proposed. A fat-free paper was devised by 
Schleicher and Schull to secure greater accuracy in estimating the 
milk fat. In the place of blotting paper other substances have been 
used such as pumice stone, kaoline, plaster of Paris, kieselguhr, as- 
bestos etc. 

Babcock asbestos method. — Official. — "Extract the residue from 
the determination of water by the Babcock asbestos method with an- 
hydrous ether until all the fat is removed, evaporate the ether, dry 
(lie fat at the temperature of boiling water, and weigh. The fat may 
also be determined by difference, drying the extracted cylinders at 
the temperature of boiling water." 

Paper coil method. — Official. — "Make coils of thick paper, cut into 
strips 6.25 by 62.5 cm., and thoroughly extract with ether and alcohol, 
or correct the weight of the extract by a constant obtained for the 
paper. From a weighing bottle or weighing pipette transfer about 
5 gm. of milk to the coil, care being taken to keep the end of the coil 
held in the fingers dry. Dry the coil, dry end down, on a piece of 
glass at the temperature of boiling water for one hour, or, better, in 
hydrogen at the temperature of boiling water ; transfer to an extrac- 
tion apparatus, and extract with absolute ether or petroleum ether 
boiling at about 45 °C. ; dry the extracted fat and weigh." Bell, 
Storch, Soxhlet, Werner-Schmid, Ritthausen and others have devised 
other gravity methods for estimating fat in milk, but the gravity 
methods already described are all that the milk inspector will need 
in practice. 

The heat evolved by hydrolysis of fat by sulphuric acid was used 
by Maumene as a test for milk fat, The method has been modified 
by Thompson, Ballantyne and Richmond, but is irregular in results 
and is not recommended. 

Densimetric method. — Richmond has found that if 200 cc. of 
milk be poured on a pleated filter all but .12 per cent of the milk 
serum runs through in 15 minutes. It appears that "if the specific 
gravity of the filtered milk less 1 be divided by .004, and the differ- 



185 

ence between the specific gravities of the milk before and after filtra- 
tion be divided by .0008, the figures so obtained represent very fairly 
the solids not fat and fat respectively." 

Ref Tactometer. — In the examination of butter fat the refractive 
index may be determined by means of a refractometer such as that of 
Wol my. The results obtained are more accurate than by the Grerber 
butyrometric method, but owing to the great care required in the 
manipulation of the method, the many different steps, the expense of 
the reagents, etc., the method is not recommended. 

Total Solids. 

The methods recommended by the Association of Official Agricul- 
tural Chemists are as follows: 

Method I. — Heat from 1 to 3 grains of milk until it ceases to lose 
weight, at the temperature of boiling water in a tared flat dish of not 
less than 5 cc. in diameter. If desired from 15 to 20 grams of pure 
dry sand may be previously placed in the dish. Cool in a dessicator 
and weigh rapidly to avoid absorption of hydroscopic moisture. 

Babcock asbestos method. — 'Provide a hollow cylinder of perforated 
sheet metal, 60 mm. long and 20 mm. in diameter, closed 5 mm. from 
one end by a disk of the same material. The perforations should be 
about .1 mm. in diameter and about .7 mm. apart. Fill, loosely with 
from 1.5 to 2.5 grams of freshly ignited woolly asbestos, free from 
fine and brittle material, cool in a desiccator and weigh. Introduce 
a weighed quantity of milk (between 3 and 5 grams) and dry at the 
temperature of boiling water to constant weight. 

The total solids of milk may also be determined by Babcock's for- 
mulas mentioned above, by the use of Richmond's slide rule or by 
Adams' gravimetric method. 

Total Proteids. 

The official method for the determination of total proteids is as 
follows. Place about 5 grains of milk in a Kjeldahl digestion flask 
and proceed without evaporation for the determination of nitrogen. 
Multiply the percentage of nitrogen by 6.25 to obtain nitrogen com- 
pounds. 

Casein. 

"The determination should be made when the milk is fresh or 
nearly so. When it is not practicable to make this determination 
within 24 hours, add 1 part of formaldehyde to 2500 parts of milk, 
and keep in a cool place. Place about 10 grains of milk in a beaker 
with about 90 cc. of water at 40° to 42° C, and add at once 1.5 cc. 
of a 10 per cent acetic acid solution. Stir with a glass rod and let 
stand from 3 to 5 minutes longer. Then decant on filter, wash two 
or three times with cold water by decantation, and transfer precipitate 
completely to filter. Wash once or twice on filter. The filtrate should 



186 

be clear or nearly so. If it be not clear when it first runs through, 
it can generally be made so by two or three repeated nitrations, after 
which the washing of the filtrate can be completed. Determine nitro- 
gen in the washed precipitate and filter paper by the Kjeldahl or 
Gunning method. To calculate the equivalent amount of casein from 
tne nitrogen multiply by 6.25. 

In working with milk which has been kept with preservatives, the 
acetic acid should be added in small proportions, a few drops at a 
time, with stirring, and the addition continued until the liquid above 
the precipitate becomes clear or nearly so." 

The following simple rule for finding the per cent of casein has 
been worked out by Van Slyke, "To find the per cent of casein in 
milk when the per cent of fat is known, subtract 3 from the per cent 
of fat in milk, multiply the result by .4 and add this result to 2.1." 

Albumin. 

The method for determining albumin in milk recommended by the 
Association of Agricultural Chemists is as follows: "Exactly neutral- 
ize with caustic alkali the filtrate obtained in the determination of 
casein, add .3 cc. of a 10 per cent solution of acetic acid and heat the 
liquid to the temperature of boiling water until the albumin is com- 
pletely precipitated, collect the precipitate on a filter, wash, and de- 
termine the nitrogen therein. Nitrogen multiplied by 6.25 equals 
albumin." 

Milk Sugar. 

"Acid mercuric nitrate. — Dissolve mercury in double its weight 
of nitric acid, specific gravity 1.42, and dilute with an equal volume 
of water. One cc. of this reagent is sufficient for the quantities of 
milk mentioned below. Larger quantities may be used without affect- 
ing the results of polarization. 

Mercuric iodide with acetic acid. — Mix 33.2 gm. of potassium 
iodide, 13.5 gm. of mercuric chloride, 20 cc. of glacial acetic acid and 
640 cc. of water. 

The milk should be at a constant temperature and its specific 
gravity determined with a delicate hydrometer. When greater ac- 
curacy is required, a pycnometer is used. 

The quantities of milk measured for polarization vary with the 
specific gravity of the milk as well as with the polariscope used. The 
quantity to be used in any case will be found in the following table : 



187 





Volume of Milk to be used 


Specific gravity 


For polariscopes of which the 

sucrose normal weight is 

16.19 gm. 


For polariscopes of which the suc- 
rose normal weight is 
26.048 gm. 


1.024 


60.0 CC 


64.4 cc 


1.026 


59.9 


64.3 


1.028 


59.8 


64.15 


1.030 


59.7 


64.0 


1.032 


59.6 


63.9 


1.034 


59.5 


63.8 


1.035 


59.35 


63.7 



Place the quantity of milk indicated in the table in a flask graduated 
at 102.4 cc. for a Laurent or 102.6 cc. for a Ventzke polariscope. 
Add 1 cc. of mercuric nitrate solution or 30 cc. of mercuric iodide 
solution (an excess of these reagents does no harm), fill to the mark, 
agitate, filter through a dry filter, and polarize. It is not necessary 
to heat before polarizing. In case a 200 mm. tube is used, divide the 
polariscope reading by 3 when the sucrose normal weight for the in- 
strument is 16.19 gm., or by 2 when the normal weight for the instru- 
ment is 26.048. When a 400 mm. tube is used these divisors become 
6 and 4 respectively. For calculation of the above table the specific 
rotary power of lactose is taken as 52.53°, and the corresponding 
number for sucrose as 66.5°. The lactose normal weight to read 100° 
on the sugar scale for Laurent instruments is 20.496, and for the 
Ventzke instruments, 32.975. In case metric flasks are used the 
weights here mentioned must be reduced accordingly." 

Method by use of Feliling's solution. — This method depends upon 
the oxidation of sugar by an alkaline copper solution, and the reduc- 
tion of copper to cuprous oxide. It is a gravimetric method and may 
be found by consulting the official methods of analysis of the Asso- 
ciation of Agricultural Chemists. The method has been variously 
modified by different investigators. 

There are still other tests for lactose but the milk inspector will 
scarcely have occasion to use more than those given above. As a 
matter of fact milk sugar is commonly determined by difference, 
subtracting the sum of the proteids. fat and ash from the total solids. 

Ash. 

The official method is as follows : "Weigh about 20 gm. of milk 
in a weighed dish, add 6 cc. of nitric acid, evaporate to dryness, and 
burn at a low red heat until the ash is free from carbon." The method 
given by Farrington and Woll is stated as follows: "About 20 cc. 
of milk are measured into a flat bottom porcelain dish and weighed ; 
about .5 cc. of 30 per cent acetic acid is added, and the milk first 
dried on water bath, and then ignited in a muffle oven at a low red 
heat." 



188 



Other Constituents. 



Lecithin is perhaps best estimated by the determination of phos- 
phoglyceric acid. One hundred cc. of milk is added to a mixture of 
100 cc. of alcohol, 100 cc. of water, and 10 drops of acetic acid. The 
coagulum is separated by nitration and extracted with alcohol. The 
extract is evaporated to dryness and the residue taken up with ether- 
alcohol. After evaporation the residue is saponified with potassium 
or barium hydroxide and the soap decomposed with nitric acid. The 
filtrate from this is evaporated to dryness and the residue treated 
with concentrated nitric acid and potassium permanganate. The 
phosphate is then determined as magnesium pyrophosphate, which 
multiplied by the factor 1.5495, gives the amount of phosphoglyceric 
acid in the original sample. Foreign fats in butter fat may be recog- 
nized by determining the iodine number, Reichert-Meissl number, or 



by making the Polenske test. 



Acidity. 



There are three tests in common use for determining the acidity of 
milk and cream, Manns, Farrington's and Van Norman's. 

Manns acid test. — Van Slyke's description of this test is followed. 
Exactly 50 cc. of milk or cream is pipetted into a beaker. The pipette 
is then filled with distilled water and added to' the sample. Five or 
ten drops of an alcoholic solution of phenolphthalein is added, and 
the burette belonging to the apparatus is filledi to the zero mark with 
•the standard alkaline solution, and a portion of it is allowed to run 
into the beaker. A pink color appears but disappears after stirring. 
This process is repeated, gradually diminishing the amount of alkali 
added each time until the pink color does not disappear after stirring 
10 or 15 seconds. The burette is then examined to determine how 
much of the alkali was used. The per cent of acid may be calculated 
by the following formula: — per cent of acid =no. cc. of alkali X .018, 
where the sample contained 50 cc. of milk. 

Farrington's alkaline tablet test. — Farrington, Stokes, Eichler and 
others have prepared alkaline tablets to take the place of the standard 
aikaline solution of Mann's test. The neutralizer and indicator are 
combined in the tablets. Farrington's test may be used for sour cream, 
sour milk, or buttermilk. The method when a 20 cc. pipette is used 
is thus described by Farrington and Woll. "When a 20 cc. pipette 
is used for measuring the sample to be tested, the tablet solution is 
prepared by dissolving one tablet for every 17 cc. of water; for 5 
tablets 85 cc. of water are therefore taken. When made in this way, 
each cc. of solution represents .01 per cent of acid in the sample tested, 
20 cc. of cream being taken; the number of cc. required to produce 
a pink color in the sample tested as read off directly from the gradu- 
ations of the cylinder used for making the tablet solution gives the 
per cent of acid in the sample, 10 cc. being equal to .10 per cent acid, 



189 

82 cc. to .32 per cent etc." Spillman has published a slight modifi- 
cation of this method. 

Van Norman alkali test for acidity. — The original description of 
this test is as follows : 

"With a Babcock pipette measured into a white cup, or even a common 
composite sample jar, 17.6 cc. of the cream to be tested, which has been well 
stirred; rinse the pipette out with clean water, putting the rinse water into 
the cream sample and add four or five drops of Phenolphthalein indicator. 
Having filled the cylinder to the top or 100 cc. mark with the 50th normal 
alkali solution, begin pouring slowly into the cream sample, mixing with a 
rotary motion of the hand or stirring with a glass rod until there is a pink 
color noticeable, which does not disappear immediately by continued stir- 
ring. Note the number of cc. of the alkali solution required to bring about 
this result. This will indicate the number of 100th per cent of acidity, since 
1 cc. of the alkali will neutralize .01 per cent of acid when 17.6 cc. of milk 
or cream is used." 

Detection oe Preservatives and Colors. 

Boric acid and borates: — "Render decidedly alkaline with lime 
water about 25 gm. of the sample and evaporate to dryness on a water 
bath. Ignite the residue to destroy organic matter. Digest with 
about 15 cc. of water, add hydrochloric acid, drop by drop, until all 
is dissolved, and add 1 cc. in excess. Moisten a piece of delicate 
turmeric paper with the solution, if borax or boric acid is present, the 
paper on drying will acquire a peculiar red color, which is changed 
by ammonium hydroxide to a dark blue-green, but is restored by acid." 

A simple modification of this method was proposed by the N. J. 
Dairy Commissioner as stated by Farrington and Woll. "Place in 
a porcelain dish one drop of milk with two drops of strong hydro- 
chloric acid and two drops of saturated turmeric tincture, dry this 
on the water bath, cool and add a drop of ammonia by means of a 
glass rod. A slaty blue color, changing to green, is produced if borax 
is present." 

Formaldehyde. — Hehner's method. — "To the milk to be tested add 
strong commercial sulphuric acid without mixing, and at the junction 
of the two liquids a violet or blue color will appear if the milk 
contains one or more parts of formaldehyde per 10,000. This color 
is supposed to be given only when there is a trace of ferric chlorid or 
other oxidizing agent present." 

Leach's method. — "Add about 5 cc. of the distillate obtained as 
described below to an equal volume of pure milk in a porcelain casse- 
role and about 10 cc. of concentrated hydrochloric acid, containing 1 
cc. of 10 per cent ferric chlorid solution, to each 500 cc. of acid. 
Heat to 80° or 90° C. directly over the gas flame, giving the casserole 
a rotary motion to break up the curd. A violet coloration indicates 
formaldehyde. ' ' 

Official method of preparing sample. — "If the material be solid or 
semisolid macerate 200 to 300 gm. in a mortar with about 100 cc. of 



190 

water until a sufficient degree of fluidity is obtained. Transfer to a 
short-necked distilling flask of copper or glass of from 500 to 800 cc. 
capacity and make distinctly acid with phosphoric acid. Connect the 
flask with a glass condenser and distill from 40 to 50 cc' 

Benzoic acid. — "Add 5 cc. of dilute hydrochloric acid to 50 cc. of 
the milk in a flask and shake to curdle. Then add 150 cc. of ether, 
cork the flask and shake well. Break up the emulsion which forms 
by aid of a centrifuge, or if the latter is not available extract the 
curdled milk by gently shaking with successive portions of ether, 
avoiding the formation of an emulsion. Transfer the ether extract 
to a separatory funnel and separate the benzoic acid from the fat by 
shaking out with dilute ammonium hydroxide, which takes out the 
former as ammonium benzoate. Evaporate the ammoniacal solution 
in a dish over the water bath till all free ammonia has disappeared, 
but before dryness is reached add a few drops of ferric chlorid reagent. 
The characteristic flesh-colored precipitate indicates benzoic acid. 
Care should be taken not to add ferric chlorid until all the ammonia 
has been driven off, otherwise a precipitate of ferric hydrate is 
formed." 

Salicylic acid. — Proceed exactly as directed for benzoic acid. On 
applying the ferric chlorid to the solution after evaporation of the 
ammonia the well known violet color indicates salicylic acid. 

Sodium carbonate. — Van Slyke gives the following test. "To 10 
cc. of milk add 10 cc. of alcohol and a. few drops of a 1 per cent solu- 
tion of rosolic acid. Carbonates are present if a, rose or red color 
appears, while pure milk shows a brownish yellow color." Another 
test is given by Farrington and Woll. "100 cc. of milk to which a 
few drops of alcohol are added, are evaporated arid carefully incin- 
erated ; the proportion of carbonic acid in the ash as compared with 
that of milk of known purity, is determined. If an apparatus for the 
determination of carbonic acid is available, like the Scheibler ap- 
paratus, the per cent of carbonic acid per gm. of ash (and quart of 
milk) can be easily determined. Normal milk ash contains only a 
smail amount of carbonic acid (less than 2 per cent), presumably 
formed from the citric acid of the milk in the process of incineration." 

Fluorids. — Richmond's method for the detection of fluorids is as 
follows: "At least 25 cc. of milk should be taken, and the ash treated 
in a platinum basin with a little strong sulphuric acid. Over the top 
of the basin a watch glass coated with paraffin wax, through which a 
few lines is scratched, is placed, and a piece of ice or some cold water 
is put into the concave depression. The basin is then gently warmed 
and the watch glass exposed to the action of the fumes for 10 minutes. 
In the presence of fluorids it is seen that the glass has been etched, 
after the removal of the wax. If a drop of water is placed on the 
paraffin away from the lines scratched through it, a white film of 
silica will be formed on its surface, if fluosilicates be present. If 



191 

fluoborates be present, this drop of water will give a boric acid reac- 
tion ; in the presence of fluoborates both a fluorid and boric acid 
reaction are given by the ash of the milk." 

Other methods. — Many other methods have been proposed for the 
detection of preservatives in milk, especially formaldehyde. Accord- 
ing to a method used by Leys a colorless solution of phloroglucin (1 
gin. in 1 liter), and potash solution (one third ordinary strength) 
are used. A red color is produced if formaldehyde is present when 
25 cc. of milk, 10 cc. of the phloroglucin solution, and 5 to 10 cc. of 
the potash are shaken in a test tube, the color disappearing after a 
few minutes. Kiegler found that if phenylhydrazin and a 10 per cent 
solution of soda be added to a small portion of diluted milk, a rose 
color will result in the presence of even 2 drops of formaldehyde per 
100 cc. of milk. Leonard states that if milk treated with formalde- 
hyde be heated with an excess of hydrochloric acid containing a trace 
of bromine or ferric chlorid a violet color will result. Usually in 
making the Babcock test with milk treated with formaldehyde a dis- 
tinct violet color appears at the contact of the acid and milk. 

Detection of foreign color. — Leach's method. — "Warm about 150 
cc. of milk in a casserole over a flame and add about 5 cc. of acetic 
acid, after which slowly continue the heating nearly to the boiling 
point while stirring. Gather the curd, when possible, into one mass 
by the stirring rod, and pour off the whey. If the curd breaks up 
into small flecks separate from the whey by straining through a sieve 
or colander. Press the curd free from adhering liquid, transfer to 
a small flask, and macerate for several hours (preferably over night) 
in about 50 cc. of ether, the flask being tightly corked and shaken at 
intervals. 

Annatto. — Decant the ether extract as obtained above into an evap- 
orating dish, place on the water bath, and evaporate the ether. Make 
the fatty residue alkaline with sodium hydroxid, and pour upon a very 
small wet filter while still warm. After the solution has passed 
through, wash the fat from the filter with a stream of water and dry 
the paper. If after drying the paper is colored orange, the presence 
of annatto is indicated. Confirm by applying a drop of stannous 
chlorid solution, which, in presence of annatto, produces a character- 
istic pink on the orange-colored paper. 

Anilin orange. — The curd of an uncolored milk is perfectly white 
alter complete extraction with ether, as is also that of milk colored 
with annatto. 

If the extracted fat-free curd is distinctly dyed an orange or yellow- 
ish color, anilin orange is indicated. To confirm the presence of this 
color treat a clump of fat-free curd in a test tube with a little 
strong hydrochloric acid. If the curd immediately turns pink, the 
presence of anilin orange is assured. 



192 

Caramel. — "If the fat-free curd is colored a dull brown, caramel 
is to be suspected. Shake a lump of the curd with strong hydro- 
chloric acid in a test tube and heat gently. In the presence of caramel 
the acid solution will gradually turn a deep blue, as will also the 
white fat-free curd of uncolored milk, while the curd itself does not 
change color. It is only when this blue coloration of the acid solu- 
tion occurs in connection with a brown-colored curd, which itself does 
not ehaugc color, that caramel is to be suspected, as distinguished 
from the pink coloration produced at once under similar conditions by 
alilin orange." 

Vandriken has found that if 2 cc. of filtered butter and a like 
amount of ether be treated with 6 to 10 drops of amyl nitrite, no color 
change takes place if a coloring matter had been added to the butter, 
while uncolored butter becomes discolored. 

Detection oe Heated Miek, Dirt, Adulterants etc. 

Healed ■milk. — LefTman found that when a solution of diamido- 
benzin is added to unboiled milk, with a few drops of hydrogen 
peroxid, a deep blue color appears. This reaction does not take place 
if the milk has been heated to 180°F. Bernstein recommends the 
following test for pasteurized milk. To 50 cc. of the milk 4.5 cc of a 
normal solution of acetic acid is added, slightly shaken till the milk 
lias coagulated, filtered, and the clear filtrate heated. If the original 
milk has not been pasteurized a heavy precipitate of albumin will 
form. The higher the milk has been heated up to 90 °C. the smaller 
will be the precipitate. Above that no precipitate will occur. Such 
reagents as alcoholic tincture of guaiac resin, guaiacol, hydrochinon, 
pyrocatechin etc. will give a coloration in raw milk, probably due to 
an oxidizing ferment in raw milk. 

Storch's test for pasteurized milk. — Storch found that milk retains 
its power of reducing peroxid up to 79 °G. A hydrogen peroxid solu- 
tion is made by diluting the commercial article with 5 times its volume 
of water and adding 1 cc. of concentrated sulphuric acid per liter. A 
teaspoonful of milk is shaken in a test tube with a drop of the peroxid 
solution and 2 drops of paraphenylendiamin solution. If the milk 
colors immediately indigo blue it has not been heated. If the milk 
becomes grayish blue immediately or in half a minute, the indication 
is that it has been heated to 79° or 80°C. If it retains its original 
unite color or is colored slightly violet red, it has been heated to 
more than 80 °C. 

Added water. — The Zeiss immersion ref Tactometer test is made as 
follows: "To 100 cc. of milk at a temperature of about 20°C. add 
2 cc. of 25 per cent acetic acid (sp. gr. 1.035) in a beaker, and heat 
the beaker, covered with a watch glass, in a water bath for 20 minutes 
a I a temperature of 70 °C. Place the beaker in ice water for 10 
minutes and separate the curd from the serum by filtering through 



193 

a 12.5 cm. folded filter. Transfer about 35 cc. of the serum to one 
of the beakers that accompanies the control temperature bath used 
iu connection with the Zeiss immersion refractometer, and take the 
refractometer reading at exactly 20 °C, using a thermometer gradu- 
ated to tenths of a degree. A reading below 39 indicates added 
water; between 39 and 40 the sample is suspicious." Leach and 
Lythgoe obtained no refractometer reading with pure milk below 39. 

Wisconsin curd test. — Cheese makers are frequently annoyed with 
gassy curds and it became important to devise a test by which such 
milk could be detected. A good test for this purpose was devised in 
the Wisconsin dairy school. 

To make the test a fruit jar is filled half full of milk and set in a tub 
about half full of water sufficiently warm to raise the temperature of the 
milk to 98 °F. When this temperature is reached 10 drops of rennet extract 
is added to the milk and the jar left undisturbed until the milk is curdled, 
when the curd is broken into small pieces by stirring with a case knife. The 
whey is poured off as soon as the curd settles, and this process is repeated 
at frequent intervals until the curd mats into a solid mass. The temperature 
of the surrounding water should be maintained from 6 to 8 hours, to favor 
the rapid development of the organisms in the curd. 

"If the milk contains no deleterious bacteria, the curd when cut will pre- 
sent a firm, even texture. If gas-producing bacteria are present the texture 
of the curd will be more spongy, the cut surface showing a number of holes 
varying in size, depending upon the prevalence and pas-producing ability of 
the undesirable bacteria. . . . The conditions under which the curd test 
is conducted accelerate the fermentative action, so that a milk that might 
show no symptoms of gas formation until the cheese was on the shelf would 
be detected when subjected to the curd test. Milks that are sufficiently con- 
taminated to produce floating curds will show a very spongy texture in the 
test in a few hours. No hard and fast rules can be given for the interpre- 
tation of the results of the curd test, but an ordinary operator will very 
quickly learn to discriminate between milks that should and should not be 
accepted. ... It is also possible that taints may be produced by bac- 
terial decomposition in cases where no gas is formed. This is particularly 
true with that class of organisms that act upon the albumen and casein in- 
stead of the milk sugar. Those bacteria that find their way into the milk 
through the introduction of filth and dust are particularly prone to produce 
this change, and this type of fermentation is very often found during the 
summer months. In the curd tests such milks are not condemned upon the 
texture of the curd, but upon the odor, which is more or less pronounced 
when the bottle is opened." 

Gerbers fermentation test. — This test as described by Yan Slyke 
may be made as follows : "This test consists in heating milk in tubes 
6 hours at 104° to 106 °F. and then observing the odor, flavor, ap- 
pearance, etc., for abnormal qualities. The milk is heated a second 
time at 104° to 106 °F. Any abnormal coagulation of the milk is 
noted, such as holes due to gas. Gerber states that milk coagulating 
in less than 12 hours is abnormal, due either to the abnormal character 
of the milk itself or to improper care after being drawn. Milk that 
does not curdle within 24 to 48 hours is open to the suspicion of con- 
taining preservatives and should be examined for such substances." 



194 

Dirt test. — As recommended by Van Slyke and others a dirt test 
should also be made of market milk. A hand centrifuge has been 
placed on the market by several instrument makers. It has a speed 
much hig'her than the Babcock tester, sometimes 3000 to 8000 revolu- 
tions per minute. Electric power machines are also to be had. A true 
representative sample of the milk is taken and is whirled for several 
minutes. The sediment collects at the bottom of the tube and the 
percentage can be read by means of the scale. Simple settling and ni- 
tration methods have also been proposed for the estimation of the dirt 
in milk, but they give only approximate results. 

Starch. — Occasionally starch is added to milk to give body. Starch 
grains with their concentric striations may be recognized under the 
microscope. Moreover if milk which has been adulterated with starch 
is heated to the boiling point and then cooled a blue color develops upon 
the addition of iodine. 

Gelatine. — Stokes' test for gelatine as given by Kober is as follows : 
" Dissolve some mercury in twice its weight of strong nitric acid (sp. 
gr. 1.420) ; dilute with water to 25 times its bulk; to about 10 cc. of 
this solution add a like quantity of the cream and about 20 cc. of cold 
water; shake the mixture vigorously, leave it for five minutes; then 
filter. If much gelatine be present it will be impossible to get a clear 
filtrate. To the filtrate or a portion of it add an equal bulk of sat- 
urated aqueous solution of picric acid. If any gelatine be present a 
yellow precipitate will be immediately produced." 

Coal-tar colors. — These "are detected by adding to the milk am- 
monium hydroxid and allowing a small piece of white wool to remain 
in it over nig;ht. The dye is taken up by the wool, which acquires a 
yellow tinge. When milk contains Martin's yellow, ammonium hy- 
droxid intensifies the color and hydrochloric acid bleaches it," 

Ohromates. — Kober recommends Guerin's method', for detecting 
chromates. "To 5 to 10 cc. of milk add 2 drops of a 1 per cent solu- 
tion of sulphate of copper and 2 or 3 drops of a freshly prepared 
tincture of guaiacum. Pure milk gives a greenish color, while milk 
containing 1 part in 100,000 of chromate will give an intense blue, 
which reaches its maximum in a few minutes." 

Cream, thickeners. — Various proprietary preparations have been put 
on the market for thickening cream or restoring its consistencv, but 
most of these are based on the method of Babcock and Russell. This 
method consists in dissolving 2y 2 parts of cane sugar in 1 part of 
water, and 1 part of lime in 3 parts of water, after which the lime 
solution is strained into the sugar solution. 

Testing Milk Products for Fat. 

Condensed milk. — In using the Babcock test for determining the 
fat in condensed milk Van Slyke recommends that 9 gm. be poured in 
the test bottle, and and also 10 cc. of water and the usual amount of 



195 

acid. The test is made as for milk and the fat reading multiplied by 
2. This method can not be applied to condensed milk containing cane 
sugar. In such cases Farrington recommends that 40 gm. of con- 
densed milk be mixed with 100 cc. of water. Then 17.6 of this 
mixture is pipetted into the test bottle and 3 cc. of sulphuric acid 
added. The curd is brought into a lump by whirling at a high rate 
at a temperature of 200 °F. The liquid portion is then poured off, 10 
cc. of water and 3 cc. of sulphuric acid are added, the bottles whirled 
and the liquid portion poured off again. Then 10 cc. of water and 
17.5 cc. of acid are added and the test made as with milk. The fat 
reading is corrected by multiplying by 18 and dividing by 7. 

Butter, cream and cheese require special bottles indicating a greater 
range of fat percentage. Whey, skim milk and buttermilk require 
more care in reading the scale since the percentage of fat is very small. 

Testing cream for fat. — An excellent set of directions for testing 
cream for fat percentage has been prepared by Webster and Gray 
and is given herewith. 
"Sampling: 

(1) Uniform composition and texture of cream is necessary. 

(2) This is obtained by pouring from one pail or can to another. 

(3) Frozen cream must be thawed before it can be sampled. 

(4) Churned eream can not be successfully sampled. 

(5) The tube sampler gives surest results. 

(6) The dipper sampler does well if the cream is thoroughly mixed. 

(7) Cream adhering to outside of tubes should not get into sample jar. 

(8) The tube should be blown out with steam or rinsed with hot water 

before using each time. 

(9) Keep the top of the tube open while it goes down, so it may fill as 

fast as lowered. 

Keeping the samples: 

(1) Sample jars must have tight-fitting covers and be kept tight. 

(2) If cream is dried in bottles it is evidence that covers are not tight 

enough to prevent escape of moisture. 

(3) Preservatives must be thoroughly mixed with cream; if too thick, 

heat the jars. 

(4) Do not shake the bottle to mix the cream; give it a rotary motion. 

(5) It is best to have samples protected from extreme heat or cold. 

(6) Churned cream gives only approximate results; dried cream gives 

too high results. 

(7) Extreme hot weather and lack of attention may cause separation of 

whey. 

(8) Do not take too large samples; it is a waste of cream. 

(9) Look after samples every day and see that they are in proper shape. 

Preparing sample for measuring into test bottle: 

(1) Sample must be absolutely uniform throughout. 

(2) Heat sample to about 100° P., or until it is quite fluid. 

(3) If sample is weighed, a much higher temperature may be used. 

(4) Pour from one cup to another until uniform. 

(5) The hotter the sample the more fluid it will be and the easier to 

make uniform. 

(6) Take care that no cream remains in sample jar adhering to the 

sides. 



196 

(7) If sample is lumpy, press lumps through a fine wire sieve (such as 

is used for a teapot strainer). 

(8) Melt any churned samples, mix, and sample quickly. 

(9) Make things convenient for this work and see that it is thoroughly 

done. 

Measuring- into test bottle: 

(1) Weighing the sample is the only method that will give correct results. 

(2) Use delicate balances and keep them in perfect order. 

(3) Test weights and scales for accuracy before using. 

(4) Torsion balances are very accurate; weigh one test at a time. 

(5) Less than 9 grams may be used, but 9 to 18 grams are more con- 

venient. 

(6) Air and gas bubbles in cream cause pipette tests to be inaccurate. 

(7) Specific gravity of cream causes pipette tests of cream to be too low. 

(8) Tables for correcting specific gravity are in use, but they do not 

correct for error caused by air and gas. 

(9) Weighing corrects all difficulties due to specific gravity and air or 

gas in cream. 

(10) Use great care to get the weights exactly right. 

Making the test: 

(1) If 18 grams of cream are used, add an equal weight of acid of 1.82 to 

1.83 specific gravity. 

(2) If 9 grams of cream are used, add an equal amount of water, then 

add acid as for 18 grams. 

(3) Use enough acid to make a clear fat column; determine by trial. 

(4) Use condensed steam or rain water for filling bottles. 

(5) After adding acid, fill bottles at once to bottom of neck with water at 

about 120 °F., and then whirl five minutes. 

(6) Then add water of same temperature to bring fat within scale, and 

whirl two minutes. 

(7) Keep the temperature down to 120°F. while whirling. 

(8) Have a hole drilled in top of tester to insert thermometer. 

(9) Run the tester at as high speed as bottles will stand. 

(10) For hand tester put in boiling water when beginning the test till 

it nearly reaches the bottles. 

(11) For steam tester raise the lid slightly while making the test. 

(12) When through whirling keep tester closed, so as to maintain heat 

even as possible. 

Beading the test: 

(1) See that line between fat and water is straight, and read from bottom 

to extreme top of fat column. 

(2) Read the depth of meniscus and deduct four-fifths of it from previous 

reading. A careful operator can estimate this. 

(3) Add 0.2 per cent to the result. 

(4) For 9-gram sample, double reading before adding 0.2 per cent. 

(5) Read at a temperature close to 120°F. 

(6) If bottles are placed in bath to regulate temperature, allow them to 

stand for fifteen minutes before reading. 

The test bottles: 

(1) Use as narrow-necked bottles as possible, to get wide divisions of 

scale. 

(2) The 30 per cent 9-inch bottles graduated to 0.2 per cent are most 

accurate. 

(3) Use 9-gram charge with these, doubling the reading. 

(4) The 50 per cent 9-inch bottles are next in accuracy, graduated to 

0.5 per cent. 



197 

(5) The 30 per cent, 40 per cent, and 50 per cent 6-inch bottles are too 

inaccurate in results. 

(6) In wide necks the scale divisions are too close together and errors 

are more probable. 

(7) All bottles should be tested for correctness of calibration. 

(8) With cheap bottles nearly half are not correct. 

(9) Bottles guaranteed correct can not all be depended upon." 

In the above discussion chemical methods have been abridged as far 
as was safe. In all milk inspection practice the simplest methods are 
the ones to be used first. As a rule these are final except when doubt- 
ful results are given or litigation arises. For further details on chem- 
ical analysis and methods the inspector should consult "Dairy chemis- 
try" by Richmond, "Dairy chemistry" by Snyder, "Modern methods 
of testing milk" by Van Slyke, "Testing milk and its products" by 
Harrington and: Woll, "Milk and its relation to public health" Hygiene 
Laboratory Bui. 41, "Food analysis" by Leffman and Beam, "Foods 
and their adulterations" by Wiley, and, if familiar with German, also 
"Die Untersuchung landwirthschaftlich und gewerblich wichtiger 
Stoffe" by Konig, "Lehrbuch der Nahrung'schemie" by Rottger and 
"Methoden der praktischen Hygiene" by Lehmann. 



198 



CHAPTER XII. 

BACTERIOLOGY OF MILK. 

Modern scientific investigation has made known the omnipresence 
and immense importance of bacteria in daily life. These micro- 
organisms have been shown by thousands of careful microscopic and 
bacteriological tests to be the direct and efficient cause of a great 
variety of changes in organic substances and of many diseases in man, 
other animals and plants. In scientific and popular literature relat- 
ing to bacteria they are commonly referred to as germs, microbes, 
micro-organisms and bacteria. 

Nature and Classification of Bacteria. 

Bacteria are unicellular plants of microscopic size and constitute 
the lowest order of plant; structures, standing in many respects on 
the border land between the animal and plant kingdoms. They con- 
sist of an internal substance known as protoplasm surrounded by a 
cell membrane and sometimes a thicker capsule. This membrane con- 
tains a modified form of cellulose similar to that found in the cell 
walls of higher plants. The capsule of bacteria in which this structure 
is recognized is apparently a thickened form of the bacterial mem- 
brane. Most plant cells contain a definite internal body known as the 
nucleus. Some dispute prevails at present on the point whether bac- 
teria contain a nucleus or not, A number of bacterial organisms have 
been shown to possess an internal structure which at least closely 
resembles the nucleus of other cells. The size of bacteria is much less 
than that of the ordinary plant cell being in average cases about one 
twenty-five thousandth of an inch, but varying considerably in this 
respect. 

The shape or form taken by various species of bacteria varies greatly 
and the classification of these organisms is based largely on the form 
and growth characters which they show under the microscope. Spher- 
ical bacteria are commonly called "cocci" or "micrococci," When these 
cocci occur in pairs they are known as "diplococci," when in chains 
"streptococci," and when in clusters like bunches of grapes "staphylo- 
cocci." The individual elements of all these forms are of course 
spherical cocci, the terms "bacilli" and "bacteria" are also used for 
bacterial organisms and refer to the shape of the micro-organisms in 
question. Short rods are called "bacteria," while the rods of medium 
length are called "bacilli," and long filaments are referred to under 
the name of "leptothrix." The rods may not be straight and if 
definite twisted or coiled forms are assumed distinct names are given 
to them. For example, the slightly curved bacterial rod is known as a 
"comma bacillus," and the cork screw shaped rod of considerable 



199 

Jength as a "spirillum." Moreover the cocci may multiply by division 
in one plane forming a. surface of spherical micro-organisms known 
as "planococci." When these cocci multiply in such a way as to form 
a mass with divisions in three dimensions, the organism is commonly 
called "sarcina." 

With regard to the cell wall of bacteria, it is a colorless membrane 
similar in physical characters to that of the cell wall of higher plants 
but considerably less permeable to fluids and chemical substances. 
The cell wall under the microscope usually appears as a single line 
but in bacteria with capsules and relatively thick membranes the cell 
wall exhibits a double contour. The protoplasm in the interior of 
the bacterial cell shows granules, occasionally a structure resembling 
a nucleus, and other anatomical features which are to be found in 
higher plants. 

Bacteria may be motile or non-motile. That is, under the micro- 
scope they may or may not show spontaneous movements. Cocci 
usually exhibit a continuous movement known as the brownian motion, 
which has not been definitely explained. Many bacteria exhibit spon- 
taneous movements which are due to the lashing motion of flagella or 
minute hairs which proect outward from the cell membrane. 

Reproduction. — Bacteria multiply by division or fission of the indi- 
vidual cells. Under favorable conditions of growth as soon as a cell 
has reached its normal size it divides into two by the formation of a 
cell membrane separating the two daughter cells. The different planes 
or directions in which the divisions or walls are formed determine 
the shape of the colony of bacteria and the disposition of the individual 
members of the colony. All plant and animal tissues multiply in 
essentially the same way but the process can be observed more easily 
under the microscope in the case of such simple organisms as bacteria. 
The time which elapses between cell divisions is in a large part depend- 
ent upon the conditions under which the bacteria are maintained. As 
a general rule the period is not over half an hour and in many cases 
may not be more than twenty minutes. If the average period is 
assumed to be thirty minutes it may be determined easily by a theo- 
retical calculation that in twenty-four hours one single bacterial cell 
would produce 281,000,000,000 bacteria. As a matter of fact how- 
ever the multiplication is never as rapid as such a theoretical calcula- 
tion would show, for there are always some agencies which reduce 
the possible rate of multiplication. It is apparent however that under 
ordinary conditions not only the number of bacteria present in a 
suitable nutrient medium will increase enormously within a relatively 
short period, but also that the actual weight of the bacterial mass in 
such a medium will increase correspondingly. Certain species of 
bacteria, particularly cladothrix do not divide in the strict sense of 
the term but grow rapidly in length, giving rise to branched threads 
during this growth. 



200 

Bacteria exist not only in the ordinary condition of vegetative 
cells, multiplying by division, but also form spores and are able to 
reproduce themselves by these bodies. Bacterial spores in a physio- 
logical sense are to be compared, with the seed of higher plants and 
by means of them bacteria are not only able to reproduce themselves 
but to protect themselves against unfavorable conditions which would be 
fatal to mere vegetative cells. The spores of bacteria are of two kinds, 
one known as endospores, which form inside the vegetative cell by the 
accumulation into a more or less spherical mass of a portion of the 
cell. The protoplasm in spores is apparently in a resting stage and 
is surrounded by a tough membrane which protects them against heat, 
desiccation, sunlight and antiseptic substances. In certain cases 
other kind of spores is formed and is known as "arthrospores." These 
are distinct from endospores by the fact that the whole vegetative 
cell becomes gradually modified into a spore by the formation of a 
thickened membrane and with a physiological modification of the 
contained protoplasm. The spores may be blown about by the wind, 
carried in dust or water and may lie in this way for an indefinite 
period provided favorable conditions for germination are not presented. 
As soon .as the proper conditions for growth are found the spores 
germinate, producing ordinary vegetative cells which multiply in 
the ordinary manner as long as suitable conditions remain. The 
possible length of life of such spores under conditions not favorable 
for germination varies greatly in different species of bacteria but in 
the case of anthrax bacillus has been shown to be at least as long as 
eighteen years. Not all bacteria form spores. The cocci as a class 
are without spores but the bacilli and bacteria may or may not form 
spores. Among the spore-bearing bacteria familiar examples are 
found in the bacilli of anthrax, tetanus, malignant edema and black 
ieg. Some of the bacteria which are commonly found in milk form 
spores while others do not. The spore-bearing bacteria are the ones 
which furnish difficulty in a successful pasteurization of milk. 

It is apparent from the above considerations that there are much 
greater dangers from infection of milk or other food substances or 
from the mere presence of material containing spores in milking 
stables and milk rooms than from ordinary bacteria which do not 
form spores. The vegetative cells of bacteria are readily attenuated 
or killed by desiccation, the action of sunlight or a temperature of 
150 degrees F. for a period of ten minutes or more. Momentary 
subjection of milk containing vegetative bacteria to a temperature at 
the boiling point is sufficient to kill these organisms. Spores on the 
other hand may resist a boiling temperature for several hours. In 
fact live steam at a temperature of 230 to 240 F may be required 
io kill them. With dry heat even higher temperatures are necessary. 

Bacteria like other plants require a certain set of conditions in their 
environment in order to thrive and multiply successfully. They re- 
quire for example the presence of certain elements which are recog- 



201 

nized as necessary to plant growth. These include oxygen, hydrogen, 
carbon, nitrogen, sulphur, phosphorus, potash, lime, magnesium and 
iron. Since bacteria do not possess chlorophyll they are not able to 
obtain their carbon directly from carbonic acid but depend upon the 
presence of carbohydrates, particularly sugars and starches. While 
the various plant foods mentioned above are necessary for the growth 
of bacteria, these micro-organisms cannot multiply in substances in 
which these elements exist in .a too condensed form. Thus in thick 
sirups, condensed milk and similar products bacteria do not multiply 
even when inoculated into the material. As a rule bacteria thrive 
best in media which are neutral in reaction or which show a slightly 
alkaline reaction. A striking exception to this rule is seen in the 
case of Jactic acid bacteria in milk which grow and multiply rapidly 
in the acid which they have produced by their own growth in milk. 
Other bacteria, however, which normally attack protein, cause its 
decomposition with the formation of gas, and are unable to multiply 
in milk strongly acidified by the presence of the lactic acid bacteria 
until after these organisms have completed their work and the acid 
content of the milk has diminished. 

In addition to the presence of suitable food materials bacteria also 
require certain temperatures for their most rapid growth. In most 
cases the suitable temperature for the growth of bacteria may be said 
to range from 59° to 104°F, and the range is for the most part even 
narrower than that, being practically confined to 86° to 95°F. There 
are some bacteria, however, which may grow and multiply at 32° F., 
while 9 few others multiply even at a temperature of 140°F. For- 
tunately, however, the latter do not occur in milk. The figures just 
given for the temperature requirements of bacteria apply primarily 
to bacteria which do not cause disease. Pathogenic bacteria, on the 
other hand, require for the most part temperatures ranging from 95° 
to 98"F. for successful growth. 

Bacteria may be classified into the two groups saprophytes and 
parasites, according as they draw nourishment from dead or living 
substances. Saprophytes are found in all kinds of dead and decaying 
animal and vegetable substances and are therefore to be met with in 
fertile soils and filth of all sorts as well as on utensils, cloths and other 
substances which have become contaminated with organic material. 
Parasitic bacteria, on the other hand, are found in some living organ- 
ism or host. A few parasitic bacteria cause disease in plants hut 
these have no significance in milk inspection. All other parasitic 
bacteria are known as pathogenic organisms for the reason that they 
cause disease in animals. Bacteria which are able to live only in 
dead organic material are known as "obligate saprophytes," and those 
which can live only in an animal body are known as "obligate para- 
sites." Bacteria however which are ordinarily saphophytic but may 
aiso grow and multiply in living animal tissue are known as "faculta- 
tive saphophytes," and pathogenic bacteria which may occasionally 



202 

live in dead organic substances are known as "facultative parasites." 

Bacteria are furthermore divided into aerobes and anaerobes, Re- 
cording as they require the presence or absence of free oxygen in the 
nutrient medium for successful growth. Aerobic bacteria are unable 
to grow in the absence of oxygen, while anaerobic bacteria are des- 
troyed by the presence of free oxygen. Some aerobes, however, may 
occasionally grow in the absence of oxygen and are known as "facul- 
tative aerobes," while certain anaerobic bacteria may grow in the 
presence of oxygen and are known as "facultative anaerobes." 

The growth of bacteria brings about a variety of changes in the 
nutrient medium or any substance in which they may be found. Some 
of these micro-organisms produce fermentations, others light, still 
others color and a further important class produces gas. This varia- 
tion in the effect of the growth of bacteria upon the nutrient medium 
into which they are inoculated is of great value in the recognition of 
different, species. 

As already indicated, bacteria like other plant organisms are sub- 
ject to various influences which may affect their growth activities. 
As a rule the powers of resistance of bacteria toward unfavorable 
conditions are comparatively high, particularly in the case of those 
species which form spores. Brief mention has already been made of 
the effect of heat upon bacteria. It has been shown that spores are 
able to resist a dry heat of 266 degrees F. for one hour, and that for 
the certain sterilization of dry material contaminated with such 
spores a temperature of 350 degrees F. is required for half an hour. 
On the other hand nearly all bacteria without spores are killed by 
subjection to a temperature of 140 to 158 F. for a period of ten 
minutes. The great difference in the resisting power of bacterial 
spores and vegetative bacterial cells has suggested the adoption of 
the method of so-called fractional sterilization for destroying these 
organisms in milk and other substances'. If for example, milk con- 
taining spore-bearing bacteria is subjected to a temperature of 150°F., 
all of the vegetative cells are destroyed, while the spores are unaffected. 
These spores however will germinate in the course of another twenty- 
four hours, at which time the material should be again subjected to a 
temperature of 150° for a period of ten minutes. The process is 
usually repeated for several days in order to make sure of complete 
sterilization. This method is in common use in the sterilization of 
nutrient media intended for inoculation with bacteria which are to 
be studied. It is based on the assumption, which has ,been proved 
to be correct, that by repeatedly applying heat at intervals sufficient 
to allow the gerVnination of spores but not to permit the formation 
of new spores, the material may thus be rendered absolutely sterile. 

Bacteria are not susceptible to the influence of cold. It is often 
popularly supposed that bacteria may be destroyed by extremely low 
temperatures. Such, however, has been found not to be the case. The 
Boston Board of Health has carried on a long series of observations 



203 

upon the bacterial content of water obtained from thawing ice. The 
bacteria originally present in water and caught in ice are not greatly 
affected by the freezing process and begin to multiply again vigor- 
ously as soon as furnished a satisfactory temperature for growth. By 
means of liquid air temperatures far below those which ever occur 
in nature have been produced and bacteria have been subjected to 
these extremely low temperatures without thereby losing their vitality. 
It is apparent, therefore, that freezing temperatures cannot be consid- 
ered as having any antiseptic effect upon ordinary bacteria. 

Direct sunlight exercises a marked effect in attenuating or destroy- 
ing bacteria. In fact sunlight is one of the very best and most effi- 
cient antiseptic agents which can be applied to stables or other struc- 
tures which it is desired to disinfect. It is generally stated that the 
effect of light is not fully exercised if the bacteria, exist in masses 
of filth of considerable size. Recent experiments, however, have 
shown conclusively that within reasonable limits the size of particles 
of filth, sputum or animal material in which bacteria are found has 
no appreciable effect upon the influence of sunlight in destroying or 
attenuating the bacteria. It has become more and more obvious in 
recent years that stables so constructed as to permit the free access of 
sunlight niay be safely assumed to be more sanitary, even if the venti- 
lation is poor, than stables in which the ventilation is good but the 
lighting arrangements poor. 

The influence of pressure upon bacteria is very slight indeed. Ex- 
periments have been made in which anthrax bacill and other micro- 
organisms have been subjected to pressures as high as 6000 
atmospheres without killing them or appreciably affecting their 
vitality. 

The effect of X-rays upon micro-organisms has been recently quite 
extensively tested in connection with the attempted cure of various 
diseases, particularly tuberculosis, typhoid, cholera, diphtheria, an- 
thrax, rabies, etc. The results obtained in these experiments are not 
in harmony. A few investigators have claimed remarkable effects 
from X-rays in the destruction of bacteria lying at considerable depths 
underneath the skin of the living body. This is particularly true in 
cases of lupus. It is impossible however to make any practical use 
of X-rays in dairying, even if this agent should be proved to have an 
important antiseptic effect. 

For twenty years or more experiments have been carried on with 
electric currents in sterilizing water, milk and other liquids. Averag- 
ing the results obtained with 660 samples of milk, Petersen found the 
electrical resistance of milk to be 232 ohms. Boult and Dubousquet- 
Laborderie in 1892 and 1893 studied the question of sterilizing milk 
by electricity. They found that an alternating current had no effect 
upon the bacteria in milk. A continuous current was said to destroy 
ail the bacteria on account of the heat developed by the electric current, 



204 

but some electrolysis of the milk took place. The process was patented 
in 1893. 

Drown and others found the purification of water by electricity to 
be impracticable. Willson patented in 1906 a process for separating 
the casein by electroylsis. 

Recently a process for sterilizing milk by electricity has been pat- 
ented by Goucher. A number of machines made by this company are 
already in use, one having been purchased in Honolulu. In the 
circulars sent out by the Goucher Electric Purifying Co., the claim 
is made that "the milk is brought to a state of absolute sterility" and 
that "its digestive properties are enhanced to the maximum." In a 
report of the Lederle Laboratory on milk purified by the Goucher 
process it is stated that the milk on issuing from the machine has a 
temperature of 155°-161°F., and that an alternating current is used 
of 1920-1960 voltage and 7.5-8.5 amperage. In one test milk con- 
taining 2,970,00.0 bacteria per cc. showed 172,000 bacteria per cc. 
after being "purified." In another test the bacteria in raw and "puri- 
fied" milk was 2,700,000 and 58,000 per cc, respectively, and in a 
third 520,000 and 18,000. It is stated that nearly all of the tubercle 
bacilli and streptococci, 97 per cent of the staphylococci and 98.8 per 
cent of the typhoid bacilli were killed by electric purification. Better 
results may be obtained in the future but the old adage that "pure 
milk is better than purified milk" is still true. The results given by 
this machine at present are highly satisfactory. 

Bacteriologists have made experiments to determine the effect of 
mechanical shock by the production of currents and other mechanical 
movements in media containing bacteria. The results obtained from 
these experiments are somewhat antagonistic. Certain species of 
bacteria appear to thrive best in media which are completely at rest 
and are considerably checked in their development when the media 
are shaken or subjected to other mechanical movements. Thus in 
one experiment the continued shaking of a culture containing Bacillus 
subtilis for four days was sufficient to destroy the bacteria. It is 
unnecessary to discuss in this connection the effects of chemical anti- 
septics upon bacteria. Many of these are known to exercise a powerful 
effect upon the bacteria, destroying them even when used in diluted 
solutions. This matter has been discussed in chapter III in connection 
with an account of the disinfection of stables after the prevalence of 
infection diseases. The disinfectants commonly used for destroying 
bacteria are corrosive sublimate, formalin, carbolic acid, lime, copper 
sulphate, permanganate of potash, borax, etc. Disinfectants, how- 
ever, cannot be used in milk on account of their harmful properties in 
human beings. The conclusion has been repeatedly reached in dis- 
cussing this matter from different standpoints that when proper pre- 
cautions are observed milk may be drawn with only an exceedingly 
small number of comparatively harmless bacteria in it. If the milk 
is then cooled to a temperature of 40°F. and kept at a. low temperature 



205 

until consumed, the few bacteria present in it when drawn will not 
have an opportunity to multiply. If, on the other hand,, on account of 
carelessness or accident the milk becomes contaminated, the only per- 
missible means of sterilizing it is by the application of heat. 

Sources of Bacteria. 

Normal udders. — As shown by Conn and various other investigators 
of dairy problems, milk is secreted in the normal udder entirely free 
from bacteria. Numerous investigations in recent years have demon- 
strated the truth of this statement, although it has been many times 
doubted on account of the great difficulty encountered in obtaining 
perfectly aseptic milk from the udder. At first various attempts 
were made to drawn milk from the udder under sterile conditions so 
as to permit of no contamination from external sources. Although 
many of these attempts were failures, success was had in many in- 
stances and enough proof has been adduced to show that milk at the 
moment of its secretion in the secretory tissue of the udder of normal 
cows does not contain bacteria. In other words the healthy udder 
does not secrete bacteria with the milk and we are therefore forced 
to the conclusion that all bacteria which find their way into the milk 
of healthy cows must come from outside sources. Attention has al- 
ready been called to the fact that the udder may be invaded to a greater 
or less depth by bacteria which gain entrance from the outside. In 
order to determine the extent of this invasion the utmost precautions 
ninst be taken to prevent the introduction of bacteria with instruments 
used in obaining samples of milk from different parts of the udder. 
This matter has been thoroughly investigated by Ward, Grotenfelt, 
Freudenreich, Moore and many others. Ward made a study of the 
lactiferous ducts of 19 cows and found them to contain bacteria 
throughout their whole length. It was shown during this investigation 
that milk is sterile when secreted by the mammary glands of healthy 
cows but may at once become contaminated by bacteria which are 
always present in the smaller milk ducts of the udder. In Ward's 
investigations the bacteria found in the interior of the udder were 
not such as affect milk seriouslv. This fact however eives us no> assur- 
ance that injurious or pathogenic bacteria may not make their way 
into the udder. The fact that the udder is constantly and normally 
invaded by various bacteria gives a basis for the ordinary classification 
of a number of bacteria in the group of dairy bacteria. There are 
apparently no structures in the udder which are adapted to preventing 
the invasion of bacteria from the outside through the milk ducts of 
the teats. 

Diseased udders. — While it is true that non-pathogenic bacteria 
such as may be present in enormous numbers in the alimentary tract 
of cows are not secreted through the udder, the case is quite different 
when we come to consider pathogenic bacteria which may affect cattle, 
particularly those micro-organisms which cause abnormal conditions 



206 

ill the udder. It is impossible to make any general statement which 
would hold true regarding the possible excretion of all forms of patho- 
genic bacteria from the udder. As indicated in chapter XIII on the 
transmission of infectious diseases by milk not all disease germs 
which affect cows have been demonstrated in the milk of affected 
cows and those Avhich are found in milk are not all excreted to the 
same extent. Tubercle bacilli are found from time to time in the 
milk of tuberculous cows. This is especially the case whenever the 
udder contains a local lesion of the disease. In all such instances the 
milk commonly contains tubercle bacilli, while in other cases in which 
the udder is not involved the milk may or may not contain tubercle 
bacilli according as the disease progresses. Apparently whenever a 
Tubercle in any part of the body breaks down and the tubercle bacilli 
are thus set free into the lymph or blood, these organisms may be car- 
ried through the udder and. may there escape into the milk, especially 
if there be a mixed infection. The probability of disease germs being 
found in the milk is greatest in the case of all diseases in which 
hemorrhagic processes occur. Thus in anthrax the probability of the 
bacilli being excreted with the milk is very strong. Similarly with 
hemorrhagic septicemia. Even in the case of tetanus and rabies the 
virus of the disease might readily escape into the milk if any abnormal 
condition of the udder should exist at the same time with the primary 
disease. In the case of actinomycosis of the udder the ray fungus 
which causes the disease might easily escape from a tubercle and find 
its way into the milk. In nearly all cases of foot and mouth disease 
in which the udder is affected the virus gains entrance to the milk 
and renders it highly infectious and dangerous. Garget or mammitis 
is a very common trouble among milk cows and the milk in cases of 
this disease is almost sure to contain the specific micro-organism, if 
the disease is of the infectious form, or if other bacteria along with 
pus and disintegrated tissue are set free during the course of the 
disease. 

Exterior of cows. — As soon as milk is drawn it is subject to far 
greater likelihood of infection with bacteria of various kinds than 
could be the case while it was still retained in the udder. One of 
the most fertile sources of contamination of milk with bacteria is 
the cow herself. Some of the practical considerations in this connec- 
tion have already been discussed in chapter VI on milking and hand- 
ling of milk on the farm. The skin and hair of the cow must be 
considered as perhaps the most important source of contamination of 
milk for the reason that these parts are continually exposed to bacterial 
pollution as the result of the various forms of filth which are almost 
always attached to the cow and her hair. If the skin and hair of cows 
were contaminated but once and the moist filth on these parts were 
allowed to become thoroughly' desiccated and exposed to sunlight 
without fresh contamination, the bacteria in the filth would soon be 
destroyed or become so attenuated that they could scarcely cause ser- 



207 

ions changes in milk. In practice, however, this never occurs. Cows 
are exposed to fresh contamination many times daily. Every time 
they lie down a certain amount of dust, straw or manure becomes 
attached to the hair and skin, and more bacteria are thus placed in a 
favorable position for falling into the milk at milking time. 

Obviously there is no limitation upon the kind or nature of bac- 
teria which may be found on cows. The variety and number will 
depend in every case upon the cleanliness of stables and yards and 
the care exercised in cleaning cows. These bacteria may include not 
only the ordinary milk bacteria which produce fermentation, change 
of color, gas and other products, but also any pathogenic organisms 
which may be present as the result of disease. If cows are handled 
by attendants who have recently recovered from infectious diseases 
or who come in contact with patients suffering from such diseases 
the pathogenic micro-organisms may be transferred to the cow in such 
a position as to fall into the milk. Moreover, according to recent 
investigations of the Bureau of Animal Industry it appears that 
tubercle bacilli are almost always present in the manure of tuberculous 
cows. They find conditions in manure under which they may retain 
their vitality and virulence for long periods and it seems highly 
probable that a considerable percentage of the tubercle bacilli found 
in milk may have gained entrance to the milk by being first excreted 
in the manure in which they become plastered upon the cow to fall into 
the milk at some time later. 

The air. — The lower strata of air always contain varying numbers 
of bacteria of different sorts. The air of cities contains more than 
that in the country and the air of stables and yards more than that 
over cultivated fields and in forests. If dusty feeding stuffs are 
given to cows at or near milking time the air becomes laden with a 
quantity of dust particles carrying bacteria of various kinds. These 
may easily find their way into milk under the ordinary conditions 
which prevail on dairy farms. Moreover the bedding is almost always 
contaminated with a large number of bacteria, and, if dry and fine, 
the movements of the cows and attendants are almost sure to stir up 
sufficient dust to keep the air highly contaminated with bacteria. 
Again, in view of the fact just mentioned that tuberculous cows 
secrete bacteria in the feces, this material when dry is certain to add 
its quota to the contamination of the air. Obviously the contamina- 
tion of milk with such bacteria is a far more serious matter than 
in the case of ordinary milk bacteria. 

The large diameter of ordinary milk pails exposes a large surface 
of milk to contamination with bacteria from the air. The extent of 
exposure from this source during milking cannot be better diminished 
than by the use of covered pails as mentioned in chapter VI. For- 
tunately the micro-organisms usually found in the air of sanitary 
stables belong to species which have no serious effect on milk and are 
therefore relatively of secondary importance. A comparative test 



208 

was made by Eraser in which agar plate cultures were exposed in 
different locations to determine the number of bacteria which would 
fall upon their surfaces during different lengths of time. The average 
time of exposure was half a minute. In these experiments more 
than a thousand exjDosures were made in different locations and the 
average results obtained indicate that the number of colonies of bac- 
teria which find their way into dishes exposed under such circum- 
stances with an area of 63 square centimeters is highest under a 
comparatively clean but unwashed udder and lowest in a sanitary 
milk bottling room. The other locations compared with these were 
an open field, a barn yard, a well kept commercial barn, a university 
dairy barn, a poorly kept barn, under a washed cow's udder and 
in a dairy room. The effect of feeding roughage and brushing the 
cows shortly before milking was merely to increase the number of 
bacteria. The results obtained in these experiments showed that the 
greatest source of contamination in milk is the cow herself, particu- 
larly the udder. The number of bacteria falling upon a given sur- 
face was greatly reduced by an ordinary washing of the udder. 

The -milker. — Attention has already been called in chapter VI to 
the necessity of employing milkers with sanitary personal habits and 
with a thorough understanding of the importance of cleanliness in 
handling milk. The bacteria which the milker may contribute to milk 
depend entirely upon his habits and upon the persons and, objects with 
which he comes in contact. His hands and clothes may be contam- 
inated with the ordinary bacteria of the air and soil which cause 
relatively little serious trouble in milk. On the other hand a careless 
or insanitary milker may carry with him not only the micro-organisms 
which cause disease in animals but particularly the bacteria of typhoid, 
diphtheria, scarlet fever, cholera and other infections diseases of man. 
In this connection it should be remembered that in general the bac- 
teria which gain entrance to the milk from the clothes or person of 
the milker are more likely to be dangerous than those which come 
from the exterior of the cow and from the air. 

Milk utensils. — Pails, separators and all utensils used in handling 
milk serve as fruitful sources of contamination if they are not thor- 
oughly cleaned after each using. If milk particles are allowed to 
remain upon the surface of such utensils they may not only contain 
the bacteria present in the milk which they held at a previous using 
but may also serve to catch and hold bacteria which may gain entrance 
to such utensils between two usings. The bacteria which may thus be 
added to milk from unclean utensils may include not only the ordi- 
nary milk bacteria but various pathogenic micro-organisms. 

Stables. — In ordinary cases the stable is a source of bacterial con- 
tamination of milk only in an indirect sense in that the bacteria of 
stables may become attached to the cows from which they fall into 
the milk or may be raised in the dust of the stable and gain entrance 



209 

to the milk through the air. Obviously a large part of the bacterial 
contamination of milk from the exterior of cows and from the air may 
be prevented by careful sanitary attention to the condition of stables. 

Barnyards. — The relationship of barnyards to the bacterial con- 
tamination of milk is essentially the same as that of stables. They 
may tend to add bacteria to the milk as the result of the filth which 
becomes plastered upon the cows, or as the result of the dry contam- 
inated dust which may be blown from such locations into the milking 
stable. If barnyards are properly cleaned and drained, the amount 
of possible bacterial contamination which they contain will be greatly 
reduced. 

Bedding. — One of the essential prerequisites in a sanitary bedding 
is that it shall not be dusty and shall not be capable of being ground 
up into a fine condition. Moreover it should absorb and hold liquids. 
Ail moldy, smutty or dirty straw of other material is unsuitable for 
use as bedding in a dairy stable. Corn stalks, shavings, sawdust and 
peat moss are satisfactory materials for bedding and contain rela- 
tively little dust or filth which can give rise to bacterial contamination 
of milk. 

Water. — Nearly all water ordinarily used about cow stables and in 
milk rooms contains a certain number of bacteria. Spring water and 
water from deep wells properly protected against the reception of 
surface drainage have far less bacterial contamination than water 
which has not been filtered through the soil. The presence of ordinary 
bacteria in the drinking water of cows is of itself no source of con- 
tamination to the milk, since such bacteria do not penetrate through 
the walls of the alimentary tract and therefore cannot gain entrance 
to the milk directly through the cow. If unsterilized water, however, 
is used in washing milk vessels, these utensils may become contam- 
inated and may give rise to the infection of milk subsequently poured 
into them. A number of outbreaks of typhoid fever have been traced 
directly to the use of contaminated water in washing milk utensils. 

Contamination in handling. — The possibility of contaminating 
milk with bacteria continues until the milk is consumed. The less 
handling to which the milk is subject in open vessels, therefore, the less 
liability of contamination. If milk is poured from one vessel to 
another in the open air, there is not only the possibility of contamina- 
tion from the air, but from particles of dust or filth which may be 
shaken from the clothing of the person who handles the milk. Morer 
over with each transfer of the milk from one vessel to another there is 
the added chance of an unclean milk utensil adding its quota of bac- 
teria to the milk. If the milk is strained, cooled, bottled and sealed 
as quickly as possible and delivered to the consumer in bottles, the 
danger of contamination is much less than when it is carried in cans 
which are opened from house to house and exposed to further bacter- 
ial pollution. 



210 

Germicidal Action of Milk. 

The results obtained by various investigators in studying the bac- 
teriology of milk indicate, as stated by Stocking, that by far the 
larger part of bacteria found in milk gain access to it through external 
sources. Milk undergoes souring, changes in flavor, odor and color 
and various processes of decomposition as a result of the presence and 
growth of these bacteria. It has long been a generally accepted opin- 
ion that nearly all spores or bacteria which may find their way into 
milk, thrive and multiply in milk at a rate which depends primarily 
upon the temperature of the milk. It is also commonly believed that 
these bacteria begin to multiply as soon as they gain entrance to the 
milk and with great rapidity. This has been considered as the prime 
reason why milk should be cooled as soon as possible after being 
drawn. The assumption of the rapid multiplication of all bacteria 
in milk was somewhat thrown in doubt by the experiments of Hunzi- 
ker, in 1901, and subsequent experiments by other investigators. As 
a result of these studies it was announced that milk exercises a germi- 
cidal action upon bacteria which persists for a certain number of 
hours after it has been drawn. Careful experiments, the accuracy 
of which cannot be doubted, indicate clearly that the number of bac- 
teria in milk actually does diminish for a number of hours after it 
has been drawn until .the bacterial contamination reaches a minimum, 
after which the number of bacteria begins to increase rapidly. The 
supposed germicidal action was found to be most rapid at relatively 
high temperatures and under such conditions the minimum number 
of bacteria was reached in a few hours. If the milk was held at a 
lower temperature the intensity of the bactericidal action was less 
and the number of bacteria gradually diminished for a much longer 
time. Under ordinary conditions there was found to be a diminution 
in the number of bacteria for three to nine hours after the milk was 
drawn. 

The question of the germicidal action of milk has been thoroughly 
studied by Conn and Stocking, with the results that the facts an- 
nounced by Tlunziker and others are found to' be correct, but these 
facts receive a different explanation than that proposed by Uunziker. 
In the recent investigations by Stocking it appears that while milk 
a few hours old contains a smaller number of bacteria than it did 
when first drawn from the cow, this is due to the relative adapta- 
bility of different species to continued growth in milk. Some kinds 
of bacteria find milk a very unfavorable medium in which to grow 
and Conn and others have shown that milk at the curdling point 
contains relatively few species of bacteria, frequently only two or 
three. This means that nearly all of the species of bacteria have 
disappeared. Some of them can not grow in milk and disappear very 
soon after finding their way into it. Other species grow slowly but 
gradually disappear. A few other kinds of bacteria find milk a 
very favorable medium and multiply quite rapidly. It is easy to 



211 

understand, therefore, that the death and disappearance of the major- 
ity of species of bacteria in milk might for some time more than 
counterbalance the multiplication of the few species which naturally 
thrive in milk. This would account for the gradual diminution of the 
total number of bacteria in the milk for a limited time without making 
ihe assumption of any germicidal property of milk. Accordingly 
Stocking recommends the continuance of the practice of immediately 
cooling milk in order to hold in check the multiplication of the typical 
lactic acid bacteria which may be expected to and actually do increase 
from the moment in which they gain entrance to the milk. 

Classification of Milk Bacteria. 

Several attempts have been made to classify into more or less 
natural groups the bacteria which have been found in milk. On ac- 
count of the uncertainty which still prevails regarding the classifica- 
tion of bacteria in general and the significance of species among bac- 
teria., such attempts have sometimes been considered premature. 
Systems of classsification of milk bacteria may be rather artificial, 
but at any rate are of use in a practical way in the separation and 
study of different forms with special regard to their relative harm- 
fulness and the various effects which they produce in milk. Perhaps 
the most extensive and successful attempt at a workable classification 
of milk bacteria has been made by Conn and the results which he and 
his associates have obtained have been freely utilized in the following 
paragraphs. 

The hacillus lactis acidi group. — When grown on litmus gelatine 
the organisms of this group appear as small opaque colonies under 
the surface, with spines at the edge and of a red color surrounded by 
a red halo. This type is the most universally distributed of all the 
lactic acid bacteria and shows considerable variation in its power of 
curdling milk. Sometimes the milk is curdled rapidly, sometimes 
slowly and occasionally not at all. A small subgroup of the Bacillus 
lactis acidi type differs from the typical form in producing exceed- 
ingly small colonies on litmus gelatine, transparent and commonly 
invisible to the naked eye. It is less acid than the typical form and 
the spines at the edge of the colony are wanting. This form is rarely 
found in fresh milk, but appears to be common in milk klept for 
&ome time, especially if maintained at relatively high temperatures. 

The Bacillus lactis aerogenes group. — The name adopted for this 
group is that of the typical species which is non-motile, produces 
lactic acid, does not readily curdle milk and ferments milk sugar with 
the production of gas. On litmus gelatine the colonies are of fair size, 
appear both under and on the surface and surrounded by a bright red 
ring. The acid ring is much more striking than in the bacillus lactis 
acidi group. The acid reaction is most striking at first. After several 
days the red color disappears and the litmus turns blue. Some 



212 

colonies which are to be classified in this group prove to he Bacillus 
coli cummums. Occasionally colonies of bacilli are found which pro- 
duce acid but do not appear to agree well with the characters of the 
groups of lactic acid bacteria mentioned above. 

Streptococcus group. — The colonies of this group are not character- 
istic, being opaque, small and round if under the surface, but spread- 
ing over the surface to form a white mass. The reaction is never 
acid and rarely alkaline. At least four species of streptococcus are 
to be placed in this group and a number of bacilli are also classified 
with them on account of their action on milk. While most of the 
characters are negative this serves in an entirely satisfactory way to 
differentiate the group. None of the species produces enzymes, 
putrefaction or any visible changes in the milk, and the colonies are 
neutral in reaction. The organisms belonging to this group may be 
found in the milk ducts and are in all cases most abundant in fresh 
milk, disappearing in large part in older milk when the lactic acid, 
bacteria have multiplied in abundance. 

Yellow coccus group. — The organisms of this group produce yellow 
colonies both below and on the surface of litmus gelatine. There are 
apparently two types of microorganisms in the group, one producing 
acid and the other not, while neither curdles milk. The effect of the 
growth of these organisms on milk is very slight. Most of the micro- 
organisms are micrococci, while some appear to be sarcina. 

Rapid liquifying group. — The bacteria included in this group are 
characterized by the fact that gelatine is rapidly liquified. A single 
colony will liquify a whole gelatine plate in two or three days. All of 
the organisms belonging to the group are decidedly putrefactive and 
if present in large numbers cause very undesirable changes in the 
milk. Fortunately they are rarely numerous in milk, but strongly 
antagonized by the presence of lactic acid bacteria so that they grad- 
ually disappear in old samples of milk. The presence of bacteria 
belonging to this group, the commonest species of which are Bacillus 
fluorescens liquefaciens and Bacillus suhtilis, furnishes difficulty in 
all bacteriological examination of milk for the reason that the gelatine 
may be completely liquified before "colonies of other bacteria are ready 
for study. 

Slow liquifying group. — A number of organisms have been grouped 
together by Conn under this head for the reason that they liquify gela- 
tine very slowly, often producing only small pits after a week's growth. 
Their presence on a gelatine plate, therefore, does not greatly inter- 
fore with the study of colonies of other bacteria. Like the rapid 
liquifying bacteria they are most numerous in fresh milk, being dis- 
placed by lactic acid bacteria as souring takes place. All of the 
organisms of the group produce enzymes and cause a greater or less 
amount of putrefaction. These organisms do not come from the 
milk ducts and their presence in a sample of milk should render the 



213 

milk somewhat suspicious. It indicates at least a carelessness in 
handling milk since they must have gained their entrance to the 
milk in filth from the outside. 

The bacteria which occur in milk may also be roughly classified 
into two general groups according as they are saphophytes or para- 
sites. The parasitic bacteria are in many respects of most importance 
in milk for the reason that they are pathogenic or produce disease in 
man and animals. In the following paragraphs descriptions are 
given of the morphological characters, biology and behavior of the 
pathogenic and saprophytic bacteria commonly found in milk. The 
descriptions of the pathogenic bacteria are compiled from numerous 
original sources, including Swithinbank, while descriptions of the 
ordinary bacteria are condensed from those given in the excellent 
classification of milk bacteria by Conn in the 18th report of the 
Storrs Agricultural Experiment Station. 

Pathogenic Bacteria Most Frequently Found in Milk. 

Bacillus tuberculosis Koch. 

Morphology.— Slender, slightly bent, pointed ends, sometimes threads and 
branched forms, or club forms, longer in milk than in tissues, occurring 
singly or in twos, threes or colonies. Size 1.5-4 X. 4m*. Acid — fast. Gram 
and Ziehl-Neelsen stains positive. No spores or flagella. Non-motile. Cap- 
sule stains. Bouillon. — Growth in 7 or 8 days if glycerine is added. Some- 
times pellicle. Glycerine-agar. — Growth begins in 6-12 days. Colonies minute, 
whitish-yellow, later brown, lichen-like, elevated, sinuate, dry or moist. Po- 
tato. — Decided growth in 2 or 3 weeks, best if potato is moist, small crumb- 
like masses, friable, yellow, dull. Blood serum. — Growth begins in 10-12 days. 
Serum not liquefied. Colonies light, dry, crumb-like coalescing scales. Path- 
ogenic for man and other animals. Aerobe. — Growth from 22°-42°C, but 
best at 37°C. 
B. typhosus Eberth. 

Morphology. — Takes ordinary stains, Gram stain negative. Short, plump 
rods, longer in cultures. Size l-3X.6-.8m. Capsule. Motile, 8-14 long flagella. 
Occurs in threads. Serpentine movements. Vacuoles in stained and un- 
stained preparations but no spores. Bouillon. — Turbidity, abundant sediment. 
Gelatine plates and tubes. — Small, yellowish-white, punctiform, raised center, 
wavy elevations under microscope. In stab cultures granular, grayish-white 
thread growth. Streak cultures similar, non-liquefying. Agar plates and 
tubes. — Colonies irregular, round, grayish-white, slightly raised, yellow lines 
extending outward from the center. In stab cultures granular, grayish, 
thread growth with irregular outline and oily lustre, later yellow. On streak 
cultures spreading, wavy, smooth edge, shiny. Milk. — Appearance unchanged, 
not coagulated, slightly acid. Potato. — Variable. Delicate and moist, grayish 
or rarely brownish. May be readily differentiated from B. coli by the fact 
that the latter coagulates milk within 48 hours with abundance of acid. B. 
typhosus grows best as aerobe but also as anaerobe and in CO . Produces 
typhoid fever in man and a fatal intoxication in animals. Grows best at 
37°C. on all ordinary media, less well on non-albuminous media. No pigment 
nor indol. No gas in lactose. 
B. diphtheriae Klebs-Loeffler. 

Morphology. — Slightly curved rods usually with one end club-shaped and 
the other pointed, or may be short wedge shaped, comma shaped, or dumb- 

* m=micron. 



214 

bell form. Size 1. 2-2 X. 3-. 5m.* Tn groups of 2-4, no long chains. Stained by 
aniline dyes. Gram, Loeffler and Nicolle. Capsule. No flagella. Non-motile. 
No spores. Bouillon. — Dust-like granules, usually pellicle. Produces indol, 
acid and nitrites. Gelatine. — Yellowish-white, slightly elevated surface, non- 
liquefying, non-characteristic. Agar plates and tubes. — In 24 hours circular, 
round, white elevated colonies with smooth edges and moist. Potato. — Little 
or no growth if acid, scanty after a few days of alkaline. Milk. — Abundant 
growth, amphoteric reaction, no curdling. Blood serum. — Rapid at 37°C. 
Characteristic within 12 hours, round, raised, grayish-white colonies, yellow- 
ish, translucent if young, moist, margin irregular, center thickened and 
opaque. Colonies not confluent, may reach size of 4 or 5 mm. Abundant 
growth on hen's eggs. Grows best at 37°C. Quickly killed at 60°C. Aerobe. 

B. enteritidis sporogenes Klein. 

Morphology. — Sometimes in chains. Size 1. 6-4. 8 X. 8m. Takes aniline dyes 
and Gram stain. Motile. Spores polar, not seen in milk cultures. Gelatine. 
— Good growth on glucose gelatine, gas, liquefaction. Agar. — Grows well in 
glucose agar with much gas. Deep colonies white by reflected light, brown 
by transmitted light. Surface colonies flat, circular, moist gray, appearing 
in 24-48 hours. Milk. — After 36 hours at 37 °C. the cream at surface is sep- 
arated by stringy, pinkish masses of coagulated casein containing gas. The 
whey is acid and contains numerous bacilli. Anaerobe. Causes death in 
guinea-pigs within 18-24 hours. 
Streptococcus of contagions mammitis. 

Morphology. — Long, undulating chains, elements lm* in diameter, shorter 
in old than in recent cases of mammitis. Aerobe or anaerobe. Takes aniline 
dyes but Gram stain poorly. Gelatine. — Small, translucent, whitish colony. 
Pellicle. Potato. — Poor growth. Bouillon. — Growth after 24 hours. Sedi- 
ment, no turbidity. Milk. — Rapid growth, curdled in 24-48 hours, strongly 
acid. Causes mammitis in cows and goats. A smaller form causes gangrenous 
mammitis in sheep. Possible cause of streptococcic sore throat in children. 

Staphylococcus pyogenes aureus. 

Morphology. — Round small cocci in masses .8m* in diameter, singly or in 
pairs, masses, or grape-like clusters. Takes ordinary stains. No flagella, 
non-motile. Bouillon. — Marked turbidity, sediment, pellicle. Agar. — Round, 
even margin, orange, granular. In stab culture feeble deep growth, good 
surface growth, smooth, shiny, orange. Similar growth in streak cultures. 
Potato. — White, then yellow, raised, shiny, later orange and dry. Milk. — Acid, 
complete curdling in 1-8 days. Grows as an aerobe, less well as an anaerobe, 
pigment only in presence of oxygen. Grows best at 37 °C. Causes suppura- 
tion in man and animals. The varieties albus and citreus are very similar 
except for forming white and yellow pigments respectively. 
Streptococcus pyogenes Rosenbach. 

Morphology. — Chains of cocci, longer in fluid than in solid media. Takes 
ordinary stains and Gram. Mucoid capsule. Bouillon. — Sediment, sometimes 
turbidity, no indol. Gelatine. — Small, white, round, flat, slow, smooth margin. 
Agar. — Small, white, granular, sometimes lobed. Gray, irregular surface in 
stab cultures. Potato. — Absent, invisible or rarely abundant. Facultative 
anaerobe. Grows best at 37 °C. Pathogenic for laboratory animals, causes 
erysipelas and suppuration in man. 
Streptococcus scarlatinae Klein and Gordon. 

Morphology. — Polymorphic streptococcus with all transition stages between 
coccus and bacillus. Coccus form prevails in bouillon, bacillus on agar. 
Takes simple stains and Gram. Bouillon. — After 24 hours at 37°C. a single, 
coherent, white-gray mass appears at base of tube, floating as a flat conglom- 
erate in the fluid medium. Gelatine. — Slow, small, gray, circular, firm edge. 
No liquefaction. Chain formation conspicuous. Agar. — After 24 hours colo- 



215 

nies are gray, granular, irregular, tuberculated; or similar without tubercles; 
or with a frill of chains around a compact center. Milk. — Rapid curdling, 
acid. Blood serum. — Good growth of colonies. Aerobe. Found in cases of 
scarlet fever and sometimes thought to be the cause of the disease. Occurs 
also in diseased udders of cows. Pathogenic for mice and rabbits. 
Spirillum cholerae asiaticae. 

Morphology. — Curved rods with rounded or pointed ends. Size . 8-5 X. 2-. 5m.* 
Often S-form. Singly or in chains. Stains by ordinary methods but not by 
Gram. Granules but no spores, motile. Gelatine. — After 24 hours at 20°-22°C. 
small, discoid, white colonies, granular, irregular border. Gelatine stab. — 
Clavate mass after 2 days. Potato. — Poor growth unless potato is alkaline, 
yellow or brown, thick streak. — Bouillon. — Rapid, little turbidity, pellicle. 
On peptone bouillon the colonies are colored red by the addition of a few 
drops of sulphuric acid. Does not live long in milk after it has begun to 
sour, but thrives well in pasteurized milk. Causes Asiatic cholera in man. 
Micrococcus raelitensis. 

On litmus-glucose-nutrose-agar plates a dense crop of colonies appears 
after 3 days. Good growth on agar slope after 2 days at 37°C. Colonies are 
small, circular and bluish. On litmus-milk growth is alkaline. Found in 
the blood and milk of goats affected with Malta fever, and causes the same 
disease in man with symptoms resembling those of typhoid fever. 

Many other pathogenic bacteria may occasionally or acidentally gain en- 
trance to milk, but this happens so rarely that no good purpose would be 
served by describing all of them in this connection. For a further discus- 
sion of the transmission of contagious diseases by milk consult Chapter XIII. 

Descriptive List of Ordinary Milk Bacteria. 

A. NON-LIQUEFYING COCCI. STREPTOCOCCI AND MICROCOCCI 
I. Types That Do Not Produce Acid. 

M. lactis rosaceus Conn. 

A pink micrococcus. Morphology. — .8m.* in diameter. Stains by the Gram 
method. Gelatine colony. — 1 mm. in size, with a nucleus and a light outer 
zone. On litmus gelatine a bluish colony, not acid. Gelatine stab. — A needle 
growth and spreading pink surface. Agar streak. — A luxuriant pink growth. 
Fermentation tubes. — No acid nor gas in sugar bouillon and no growth in 
closed arm. Bouillon. — Sediment and turbidity but no pellicle. Milk. — 
Rendered slightly acid, with pinkish sediment, becomes somewhat slimy. 
Potato. — Luxuriant, thick, pink growth. Grows at both 20° and 37°C. Aerobic. 
M. lactis citreus B. Conn. 

Yellow nonacid coccus. Morphology. — Size .8m.* No chains. Stains by 
the Gram method. Gelatine colony. — Round, yellow surface, 1 mm. in size. 
Gelatine stab. — Good needle and surface growth. Agar streak. — Luxuriant 
growth. Fermentation tubes. — No acid or gas in sugar bouillon and no growth 
in closed arm. Bouillon. — Abundant sediment and sediment and thin pellicle. 
Milk. — Rendered slightly acid but not curdled at both 20° and 37°C. Potato. — 
Abundant canary-yellow growth, potato discolored. Grows well at 20° and 
37°C. Aerobic. 
M. lactis flavns Conn. 

An orange non-acid micrococcus. Morphology. — Size .5-. 8m.* Stains by 
the Gram method. Gelatine colony. — Round, smooth, thick, homogeneous 
orange. Gelatine stab. — Good needle and surface growth, orange. Agar 
streak. — Luxuriant, moist, smooth, orange or red-brown. Fermentation tubes. 
— No acid or gas in sugar bouillon, nor growth in closed arm. Dextrose and 
lactone may be made alkaline. Bouillon. — Sediment, turbidity and pellicle, or 



216 

both latter wanting. Milk.— Acidified at 20° and 37°C. Potato.— Moderate, 
smooth, moist red-brown to orange. Grows at 20° and 37°C. Aerobic. 
M. lactis citreus Conn. 

A slimy micrococcus. Morphology.— Size .8-.9m.* Gram stain positive. 
Gelatine colony. — Thick, round, smooth, white, turning green. On litmus 
gelatine coarse. Gelatine stab. — Vigorous needle and surface growth. Agar 
streak. — Thin, spreading, white. Fermentation tubes. — No acid or gas in 
sugar bouillon nor growth in closed arm. Bouillon. — Sediment and turbidity 
but no pellicle. Milk. — No change except sliminess. Potato. — Thick, slaty 
gray growth turning blue or black, potato being discolored. Grows well at 
20° and 37°C. Aerobic. 

M. lactis arborescens Conn. 

Morphology. — 7m* in diameter. Gelatine colony. — Myceloid, 1 mm. in size, 
sometimes smooth. Gelatine stab. — Arborescent needle growth and a surface 
growth. Agar streak. — Luxuriant, smooth, moist, white. Fermentation tubes. 
—Probably no acid nor gas. Bouillon. — Turbidity, sediment and pellicle. 
Milk. — No action or slight alkalinity. Potato. — Spreading, brownish not lux- 
uriant. Grows at 20° and 37°C. Aerobic. 
Gralactococcus versicolor Lux. 

White non-acid. Morphology. — Streptococcus. Size .5-1. 5m.* Gram stain 
usually positive. Gelatine colony. — Spreading, white, yellowish or brownish, 
thin. Gelatine stab. — Abundant needle and surface growth. Agar streak. — 
white to yellowish, moist. Fermentation tubes. — No acid, gas or closed arm 
growth. Bouillon. — Sediment, turbidity but no pellicle. Milk. — No action or 
slight acidity. Potato. — Scanty, gray-white or no growth. Grows at 20° and 
37°C. Aerobic. Variety A grows luxuriantly on potato and acidifies milk 
slightly. Variety B also grows on potato and digests milk without liquefying 
gelatine. 

II. Types that Produce Acid in Dextrose and Other Sugars. 

S. lactis fulvus Conn. 

Brownish-red streptococcus. Morphology. — Size .7m.* Gram stain positive. 
Gelatine colony. — Dense, 5 mm. in diameter, thick, round, white. Acid in 
litmus gelatine. Gelatine stab. — Needle growth and thin surface growth. 
Agar streak. — Luxuriant, thick, moist, translucent, reddish-brown. Fermen- 
tation tubes. — Acid in all sugar bouillons but no gas or closed arm growth. 
Bouillon. — Sediment, turbidity but no pellicle. Milk. — Acid and curdled. Po- 
tato. — Luxuriant, brown. Grows at 20° and 37°C. Aerobic. Variety A is 
larger, with negative Gram stain and pellicle on bouillon. 

M. lactis aureus Conn. 

Yellow, acid cocci, probably non-liquefying forms of S. pyogenes aureus. 
Morphology. — Size .5-1.2m.* Gram stain positive. Gelatine colony. — Round, 
thick, smooth, translucent, lemon-yellow. Litmus gelatine acid. Gelatine 
stab. — Needle growth and yellow surface growth. Agar streak. — Luxuriant, 
thick, smooth, translucent, yellow. Fermentation tubes. — Acid in all sugar 
bouillons but no gas, occasional growth in closed arm. Bouillon. — Sediment, 
turbidity, rarely a pellicle. Milk. — Acidified but usually not curdled. Potato. 
— Discolored, usually a thick yellow growth. Grows better at 37° than at 
20°C. Facultative anaerobic. 
S. lactis aureus Conn. 

Orange red streptococcus. Morphology. — Size 1-1. 2m. Gram stain positive. 
Gelatine colony. — Round, thick, rough, opaque, creamy white. Gelatine stab. 
— Needle growth and raised surface growth, orange. Agar streak. — Luxuriant, 
rough, sometimes dull and wrinkled. Fermentation tubes. — Acid in all sugar 
solutions but no gas or closed arm growth. Bouillon. — Sediment, turbidity 
and later a pellicle. Milk. — Slowly acidified and curdled. Potato. — Thick, 
rough, opaque, yellow. Grows at 20° and 37°C. Aerobic. 



217 

S. lactis viscosns Conn. 

Morphology.— A streptococcus. Size .8-.9m.* Gram stain positive. Gela- 
tine colony. — Shiny, pale yellow, round or lobate, usually viscous. Gelatine 
stab. — Needle and surface growth, producing a nail culture-. Agar streak. — 
Lobate, luxuriant, viscous. Fermentation tubes.— Acid in all sugar bouillons 
and growth in the closed arm but no gas. Bouillon. — Sediment, turbidity and 
pellicle. Milk. — Acidified, curdled and rendered very slimy. Potato. — Luxur- 
iant, dull, pasty growth. Grows at 20° and 37°C. Facultative anaerobe. Va- 
riety A shows scanty, non-viscous growth on agar and no pellicle on bouillon. 
S. lacticns Kruse. 

Morphology. — Long or short chains. Size .5-lm.* Gram stain positive. 
Gelatine colony.— Minute, white, rough, dense. In litmus gelatine always 

acid. Gelatine stab. Moderate needle growth, but no surface. Agar streak. 

— Barely visible, faint film. Fermentation tubes. — Acid in all sugars, usually 
growth in closed arm but no gas. Bouillon. — Almost invisible, slight sedi- 
ment and turbidity. Milk.— Promptly acidified and curdled. Potato.— Usually 
invisible. This species sometimes comprises 99 per cent of all the bacteria 
in a sample of milk. The tpye S. lacticus I produces acid in dextrose but 
not in other sugars. Variety A of this type shows no turbidity but a slight 
pellicle in bouillon, variety B. turbidity but no pellicle, variety C turbidity and 
pellicle with negative Gram stain, variety D luxuriant growth on potato. The 
type S. lacticus II produces acid in lactose and saccharose but not in dextrose. 
Gram stain negative. S. lacticus III shows pellicle on bouillon and acidifies 
or curdles milk. 

M. lactis acidi. 

Morphology. — Micrococcus. Size .5-1. 2m.* Gram stain positive. Gelatine 
colony. — Round, thin, smooth, white, not characteristic. No acid on litmus 
gelatine. Gelatine stab. — Needle and surface growth.' Agar streak. — Moder- 
ate, white, smooth or rough. Fermentation tubes. — Acid in all sugars but no 
gas or closed arm growth. Bouillon. — Sediment and turbidity but no pellicle. 
Milk. — Sometimes acid sometimes not, usually not curdled. Potato. — Scanty 
or absent, white. Grows at 20° and 37°C. Aerobic. Constantly found in 
fresh milk. 
M. lactis gigas Conn. 

Morphology. — Size 1.5m.* Gram stain positive. No chains. Gelatine col- 
ony . — Round, thick, homogeneous, translucent, cream-white. Gelatine stab. — 
Needle growth but no surface. Agar streak. — Scanty, beaded, translucent 
white. Fermentation tubes. — Acid in all sugars, no gas or growth in closed 
arm. Bouillon. — Sediment but no turbidity or pellicle. Milk. — Slightly acidi- 
fied. Potato. — No growth. Grows at 20° and 37 °C. Aerobe or facultative 
anaerobe. 

B. LIQUEFYING COCCI. STREPTOCOCCI AND MICROCOCCI. 
I. No Acidity in Sugars. 
M. lactis erythrogenes (Grotenfeldt) Conn. 

Pink fluorescent coccus. Morphology. — .8m.* No chains. Gelatine colony. 
— Smooth, flat, reaching .5 mm. in 4 days. Gelatine stab. — Needle growth 
with slow liquefaction and dense scum. Agar streak. — Luxuriant, white or 
yellowish, pink fluorescence. Fermentation tubes. — No acid or gas.. Bouil- 
lon. — Sediment, turbidity, no pellicle. Milk. — Slightly acidified and digested. 
Potato. — Luxuriant, yellow, moist. Grows at 20° and 37°C. Aerobic. 
M. lactis rubidns Conn. 

A red coccus. Morphology. — lm.* No chains. Gelatine colony. Rapidly 
liquefying, red. Gelatine stab. — Infundibuliform, forming red liquid. Agar 
streak. — Thick, moist, brick-red. Bouillon. — Pinkish sediment, turbidity, no 
pellicle. Milk. — No action. Potato. — Luxuriant, blood-red, spreading. Grows 
at 20° and 37°C, but no pigment at 37°C. Aerobe. 



218 

M. lactis citronus Conn. 

Orange, liquefying micrococcus. Morphology. — .8-. 9m.* Gram stain irreg- 
ular, no chains. Gelatine colony. — Yellowish, slowly liquefying, with clear 
liquid. Gelatine stab. — Liquefaction begins in 4 days. Agar streak. — Spread- 
ing, thick, smooth, orange. Fermentation tubes. — No acid, gas or closed arm 
growth. Bouillon. — Sediment, turbidity and pellicle. Milk. — No action. Po- 
tato. — Luxuriant, thick, smooth, orange-brown. Grows at 37 °C. Aerobe. 

S. lactis citreus I Conn. 

Lemon-yellow streptococcus. Morphology. — Size .6-lm.* Gram stain posi- 
tive. Gelatine colony. — Small, with clear liquid and slow liquefaction. Gela- 
tine stab. — Slow liquefaction, stratiform. Agar streak. — Luxuriant, thin lemon- 
yellow. Fermentation tubes. — No acid, gas or closed arm growth. Bouillon. — 
Sediment, turbidity and pellicle. Milk. — Slight change or digestion. Potato. 
— Luxuriant, thick lemon-yellow. Grows better at 20° than at 37°. Aerobe. 
Occasionally varieties of this species fail to liquefy gelatine, or may cause 
acid in sugars. 
S. lactis rogeri Conn. 

Lemon-yellow streptococcus. Morphology. — Size .7-lm.* Gram stain irreg- 
ular. Gelatine colony. — Thin, transparent, granular, slow liquefaction. Lit- 
mus gelatine intensely alkaline. Gelatine stab. — Needle growth, stratiform 
liquefaction. Agar streak. — Luxuriant, thick, lemon-yellow. Fermentation 
t u bes. — No acid, gas or closed arm growth. Bouillon. — Sediment and turbid- 
ity. — Milk. — Alkaline, digested, sometimes curdled. Potato. — Luxuriant, yel- 
low. Grows better at 20° than at 37°C. Aerobe. 
M. lactis niinutissimus. 

A minute coccus. Morphology. — Size .2-.3m.* Gram stain negative. Gela- 
tine colony. — Round, thin, smooth in clear pit. Gelatine stab. — Infundibuli- 
form with granular layer, sometimes a dry pit. Agar streak. — Scanty, thin, 
smooth, yellow. Fermentation tubes. — Acid in lactose, not in other sugars, 
no gas or closed arm growth. Bouillon. — Sediment, turbidity, no pellicle. 
Milk. — No change in reaction but curdling and digestion. Potato. — White, 
dry, wrinkled. Grows better at 20° than at 37 °C. Aerobe. 

M. lactis aureus A Conn. 

Yellowish micrococcus. Morphology. — Size .8-lm.* Gram stain positive. 
Gelatine colony. — V-shaped in pit with halo. Gelatine stab. — Stratiform with 
yellow sediment. Liquefaction complete in 14 days. Agar streak. — Luxuriant, 
brownish-yellow. Fermentation tubes. — No acid or gas. Bouillon.— Pellicle, 
turbidity, no sediment. Milk. — Rendered alkaline and curdled. Potato. — Lux- 
uriant, brownish-yellow. Grows at 20° and 37°C. Aerobe. 

M. lactis albus Conn. 

Morphology. — Size .7-lm.* Gram stain positive. No chains. Gelatine col- 
ony.— Round, luxuriant, thick, smooth. Gelatine stab. — Slow liquefaction, 
with dry pit. Agar streak. — Opaque, whitish, moderate, luxuriant. Fermen- 
tation tubes.— No acid, gas or closed arm growth. Bouillon.— Slight growth, 
turbidity, sediment, no pellicle. Milk.— Rendered alkaline and digested. Po- 
tato.— Luxuriant, thick, white. Grows at 20° and at 37°C. Aerobe. Six 
varieties are mentioned showing differences in viscocity, liquefaction, curd- 
ling and digestion. 

II. Acid in Dextrose or Other Sugars. 

M. lactis fluorescens Conn. 

Morphology. — Size .5-.6m.* Gram stain negative. Gelatine colony. — Round, 
moderately thick, smooth, with greenish liquefaction. Gelatine stab. — Strati- 
form. Agar streak. — Luxuriant, narrow, thick, smooth, white. Fermentation 
t u bes.— Dextrose acid, other sugars alkaline, no gas or growth in closed arm. 
Bouillon.— Sediment, turbidity, pellicle. Milk.— Acidified, curdled, digested. 
Potato.— Scanty, thin, smooth, white. Grows at 20° and 37°C. Facultative 
anaerobe. 



219 

M. lactis yariens Conn. 

Yellow coccus, common in milk.. Morphology. — Size .4-1. 4m.* Gram stain 
positive. Gelatine colony. — Deep and opaque or superficial and white, usually 
acid in litmus gelatine. Gelatine stab. — Napiform, liquefaction slow or rapid, 
sometimes a dry pit. Agar streak. — Luxuriant, rough, spreading pale orange. 
Fermentation tubes. Acid in all sugars, closed arm growth, no gas. Bouillon. 
— Plocculent sediment, slight turbidity or pellicle. Milk. — Acid, commonly 
curdled and digested. Potato. — Luxuriant or scanty, pale orange, frequently 
dry. Grows better at 37° than at 20°C. Facultative anaerobe. Variety A pro- 
duces acid only in dextrose and does not acidify milk. 
M. lactis giganteus Conn. 

Morphology.— Size 1.4-3.5m.* Gram stain positive. Gelatine colony.— 
Cloudy and white liquefying pit. Gelatine stab. — Infundibuliform, liquefac- 
tion in 1 day. Agar streak. — Smooth, orange, moderately luxuriant. Fer- 
mentation tubes. — Acid in all sugars, no gas or closed arm growth. Bouillon. 
— Sediment, no turbidity or pellicle. Milk. — Acidified, digested. Potato. — 
Scanty, beady, brownish. Grows at 20° and 37°C. Aerobe. 
M. lactis rngosns Conn. 

Perhaps M. acidi lactici Kruger. Morphology. — Size 1-1. 2m.* Gram stain 
irregular. Gelatine colony. — White pit with clear center and granular ring. 
Gelatine stab. — Slow, crateriform or stratiform. Agar streak. — Luxuriant, 
viscous, wrinkled, salmon-yellow. Bouillon. — Sediment, turbidity, ring pel- 
licle. Milk. — Acidified, curdled, not digested. Grows at 20° and 37 C C. Aerobe. 
M. lactis albidns Conn. 

Morphology. — Size .6-l.m. Gram stain positive. Gelatine colony. — Opaque, 
white, not characteristic. Gelatine stab. — Infundibuliform, liquefies in 1-3 
days, sometimes dry pit. Agar streak.— Smooth, white, not thick. Fermenta- 
tion tubes. — Acid in all sugars, no gas, usually no closed arm growth. Bouil- 
lon. — Sediment, turbidity, no pellicle. Milk. — Usually acidified and curdled, 
digestion. Potato. — Moderate, white or yellow. Grows at 20° and 37 °C. 
Facultative anaerobe. There is a variety with white growth on agar, one 
with more anaerobic character, and one which does not acidify milk. 

THE GENUS SARCINA. 
Sar. lactis alba Conn. 

White or yellow, non-liquefying. Morphology. — Size .7m.* Gram stain pos- 
itive, no motility. Gelatine colony. — Round, convex, smooth, homogenous, en- 
tire. Gelatine stab. — Needle growth, convex surface. Agar streak. — Beaded, 
raised, smooth, translucent, white moist. Fermentation tubes. — Acid and 
closed arm growth in all sugars. Bouillon. — Sediment, turbidity, no pellicle. 
Milk. — Acid, no other change. Potato. — Slight, cream-white. Grows at 20°, 
very little at 37°C. Facultative anaerobe. 
Sar. lactis lntea Conn. 

Yellow, liquefying. Morphology.— Size .7-lm.* Gram stain positive, not 
motile. Gelatine colony. — Slow liquefying pit, nucleus surrounded by gran- 
ular area. Gelatine stab. — Liquefaction in 3 weeks, crateriform. Agar streak. 
— Filiform, raised, smooth, opaque, lemon-yellow. Fermentation tubes. — No 
acid, gas or closed arm growth in any sugar. Bouillon. — Sediment, no tur- 
bidity or pellicle. Milk. — Rendered alkaline, slowly digested. Potato — Beaded, 
raised, opaque, lemon-yellow. Grows at 20° and 37°C. Aerobe. 
Sar. lactis anrantiaca Conn. 

Orange, liquefying. Morphology.— Size lm.* Gram stain positive. Not 
motile. Gelatine colony. — Liquefying pit, orange pigment. Gelatine stab. — 
Slow liquefaction, stratiform. Agar streak. — Filiform, raised, smooth, moist, 
orange. Fermentation tubes. — No acid, gas or closed arm growth in any 
sugar. Bouillon. — Pellicle, slight sediment. Milk. — No change in reaction, 
curdling, digestion. Potato. — Spreading, capitate, luxuriant. Grows at 20° and 
37°C. Aerobe. 



220 

Sar. lactis acidi Conn. 

Acid yellow. Morphology. — Size .8-lm.* Gram stain positive, not motile. 
Gelatine colony. — Round, raised, smooth, opaque, brownish. Gelatine stab. — 
Slow liquefaction or a dry pit. Agar streak. — Filiform, raised, smooth, moist, 
white or yellow. Fermentation tubes. — Acid in all sugars, no gas or closed 
arm growth. Bouillon. — Sediment, turbidity, no pellicle. Milk. — Acidified, 
not curdled or digested. Grows better at 20° than at 37 °C. Aerobe. 

NON-LIQUEFYING BACTERIA. 
I. No Acid in Any Sugar. 

B. lactis salmonis Conn. 

Salmon-colored. Morphology. — Size .6-1. 8m.* Chains. Gram stain positive. 
No spores or capsules. Gelatine colony. — Round, umbonate, lobed, white. 
Gelatine stab. — Needle growth, raised surface growth. Agar streak. — Filiform, 
thin, smooth, white to salmon. Fermentation tubes. — No acid, gas or closed 
arm growth in any sugar. Bouillon. — Flocculent sediment, membranous pel- 
licle, turbidity. Milk. — Alkaline, no other change. Potato. — Luxuriant, thick, 
contoured, pink. Grows better at 20° than at 37°C. Aerobe. 
B. lactis aureum I. 

Orange, non-acid. Morphology. — No chains. Size .7-.9Xl-3m.* Capsules, 
no spores, Gram stain positive. Gelatine colony. — Round, flat., lobed, con- 
toured. Gelatine stab. — Needle growth, thin, reddish surface. Agar streak. — 
Luxuriant, orange-brown, tough. Fermentation tube. — No acid, gas or closed 
arm growth. Bouillon. — Sediment, turbidity, pellicle. Milk. — Orange at sur- 
face, no other action. Potato. — Scanty or absent. Grows better at 20° than 
at 37°C. Aerobe. 
B. lactis citreuni II Conn. 

Yellow, non-acid. Sometimes chains. Size .5-.7X.7-1.4m.* No spores or 
capsules, Gram stain negative. Gelatine colony. — Round, opaque bead, white 
turning yellow. Gelatine stab. — Scanty needle growth, dry white surface. 
Agar streak. — Luxuriant, white to lemon-yellow. Fermentation tubes. — No 
acid, gas or closed arm growth. Bouillon.— Sediment, turbidity, flaky scum. 
Milk. — No action. Potato. — Luxuriant, yellow, thick. Grows at 20° and 37°. 
Aerobe. In some varieties the lemon-yellow is more pronounced. 

B. lactis myceloideum. 

Myceloid, no spores. Morphology. — Long filaments .7X2-3.5m.* Gram 
stain irregular. Gelatine colony. — Myceloid, 2 cm. in diameter, spreading. 
Gelatine stab. — Needle and surface growth, horizontal threads below surface. 
Agar streak. — Luxuriant, thick yellowish. Fermentation tubes. — No acid, gas 
or closed arm growth. Bouillon. — Sediment, turbidity, no pellicle. Milk. — 
Acid, not curdled. Potato.— Scanty, thin white Grows better at 20° than at 
37°C. Aerobe. 
B. lactis arborescens I Conn. 

Non-acid. Morphology. — Size .9X1.2-1. 4m.* No spores or capsules, Gram 
stain negative Gelatine colony. — Round, raised, smooth, entire, white. Gela- 
tine stab. — Arborescent needle and surface growth. Agar streak. — Scanty, 
thin, white, slightly viscous. Fermentation tubes. No acid, gas, or closed 
arm' growth. Bouillon.— Sediment, turbidity, ring pellicle. Milk.— Alkaline, 
slimy, slight digestion. Potato.— Scanty, raised, gray-brown. Grows at 20° 
and 37°C. Aerobe 
B. lactis viscosns Adametz. 

Slimy milk bacteria. Morphology.— Size .5-1.2 X.5-2.5m.* Filaments 15m* 
long. Gelatine colony.— Flat, lobate, viscous. Gelatine stab.— Needle growth 
sometimes granular, thin, shiny, gray surface Agar streak.— Luxuriant, vis- 
cous, white. Fermentation tubes.— No acid, gas or closed arm growth. Bouil- 



221 

Ion. — Sediment, turbidity, pellicle. Milk. — Alkaline, slimy, not curdled. Po- 
tato. — Thick, uneven, dirty gray Grows at 20° and 37°C. Aerobe. 

B. lactis acidi rar. E. 

Very similar to B. lactis acidi. Grows poorly on culture media. Produces 
no acid in sugars or milk. 

B. lactis connii Chester. 

Frequent in milk. Morphology. — No spores or capsules. Size .5-.7X1.4m.* 
Gram stain negative. Gelatine colony. — Round, raised, smooth, white. Gela- 
tine stab. — Needle growth, white surface. Agar streak. — Luxuriant, filiform, 
raised, smooth, white opaque. Fermentation tubes. — No acid, gas. or closed 
arm growth. Bouillon. — Sediment, turbidity, ring pellicle. Milk. — Alkaline, 
not curdled or digested. Potato. — Luxuriant, convex, smooth, white. Grows 
at 20° and 37°C. Aerobe. 

II. Acid in Dextrose or Other Sugars. 

B. rudensis connelli. 

Red, acid. Morphology. Size IX 1.8m.* No chains or spores. Gram stain 
positive. Gelatine colony. — Small, below surface, dense. Gelatine stab. — 
Needle but no surface growth. Agar streak. — Invisible or very thin. Fer- 
mentation tubes. — Acid and closed arm growth, no gas. Bouillon. — Sediment, 
turbidity, no pellicle. Milk. — Acid, curdled. Potato. — Scanty, reddish brown. 
Grows at 20° and 37°C. Facultative anaerobe. 

B. lactis catenansis Conn. 

Yellow, spore-bearing. Morphology.— Size .7 X 1.2m.* Chains. Gram stain 
negative. Gelatine colony. — Round, raised, homogeneous, transparent, yellow. 
Gelatine stab. — Needle growth, flat orange surface. Agar streak. — Orange, 
thin, sometimes wrinkled. Fermentation tubes. — Dextrose and lactose acid, 
saccharose not. No gas or closed arm growth. Bouillon. — Sediment, turbid- 
ity, pellicle. Milk. — Usually no action. Potato. — Luxuriant, wrinkled, orange 
Grows better at 20° than at 37 °C. Aerobe. 

B. lactis a.ureum II Conn. 

Orange, acid. Morphology. — Size .8-1.2 XI. 2-1. 8m.* No chains, spores or 
Gram stain. Gelatine colony. — Round, convex, smooth, entire, orange. Gela- 
tine stab. — Needle and thin surface growth. Agar streak. — Filiform, thin, 
smooth, moist. Fermentation tubes. — Dextrose acid, lactose and saccharose 
slightly so. No gas or closed arm growth. Bouillon. — Invisible. Milk. — No 
curdling or digestion. Potato. — Spreading, thin, smooth, yellow. Grows bet- 
ter at 20° than at 37°C. Aerobe. Aa variety with Gram stain positive. 

B. lactis synxanthnm. 

Morphology. — Size .8-.9X1.2-2m.* Capsule, no spores or chains. Gram stain 
negative. Gelatine colony. — Round, capitate, smooth, entire, gray. Gelatine 
stab. — Needle and raised surface growth. Agar streak. — Luxuriant, filiform, 
raised, smooth, white. Fermentation tubes. — Acid in all sugars. No gas or 
closed arm growth. Bouillon. — Sediment, turbidity, ring pellicle. Milk. — Acid, 
not curdled or digested. Potato. — Filiform, raised, contoured, gray. Grows 
at 20° and 37°C. Aerobe. 

B. seifige milch Weig. 

Morphology. — Size IX. 5m.* No spores, capsules or Gram stain. Gelatine 
colony. — Round, capitate, smooth, entire, gray-white. Acid or litmus gela- 
tine. Gelatine stab. — Needle and raised surface growth, becoming dry pit. 
Agar streak. — Filiform, thin, smooth, gray, moist. Fermentation tubes. — 
Acid in all sugars, no gas or closed arm growth. Bouillon. — Sediment, tur- 
bidity, no pellicle. Milk. — Amphoteric, yellow scum. Potato. — Filiform, thin, 
smooth, brownish. Grows at 20° and 37 °C. Aerobe. 



222 

B. lactis isignii Conn. 

Digests milk without curdling, does not liquefy gelatin. Morphology. — No 
chains. Size .5X.3m.* No spores, capsules or Gram stain. Gelatine colony. 
— Round, raised, smooth, entire, yellow. Gelatine stab. — Filiform needle 
growth, flat surface. Agar streak. — Luxuriant, filiform, raised, yellowish. 
Fermentation tubes. — Acid in all sugars after 3 days, no gas or closed arm 
growth. Bouillon. — Sediment, turbidity, pellicle. Milk. — Acid, digestion. 
Potato. — Spreading, flat, cream-white. Grows better at 20° than at 37 °C. 
Aerobe. 
B. lactis non-acidi Conn. 

Morphology. — No spores. Gram stain irregular. Size 1.8 X. 5-1. 2m.* Gel- 
atine colony. — Small, round, thick, entire, white. No acid on litmus gelatine. 
Gelatine stab. — Needle growth and spreading surface. Agar streak. — Mod- 
erate, linear, smooth, moist. Fermentation tubes. — Dextrose acid, sometimes 
lactose and saccharose. Bouillon. — Sediment, turbidity, sometimes pellicle. 
Milk. — Alkaline or no change. No digestion. Potato. — Scanty or luxuriant, 
spreading. Grows better at 20° than at 37°C. Aerobe. Appears almost con- 
stantly in milk. 
B. lactis ubiquitum. 

Morphology. — Long chains, spores, capsule. Size 1. 2-1. 4 X. 8m. Gelatine 
colony. — Round, capitate, entire, white, thin on edge. Gelatine stab. — Needle 
growth, thick surface. Agar streak. — Luxuriant, white, frost-like growths. 
Fermentation tubes. — Probably acid, no gas. Bouillon. — Sediment, turbidity, 
no pellicle. Milk. — Acid, curdling, no digestion. Potato, transparent, spread- 
ing. Grows well at 20° and 37°C. Aerobe. 

WHITE, ACID BACTERIA. 

B. lactis acidi Leichmann. 

Immensely numerous. Common cause of sour milk. Several varieties dif- 
fering from type form. Morphology. — Size .7-1.2 X.5-.8m.* Sometimes cocci. 
Gram stain positive. No motility, spores or long chains. Gelatine colony. — 
Small points, opaque, not characteristic, mostly below surface. Acid on lit- 
mus gelatine. Gelatine stab.— Granular or linear needle growth, no surface. 
Agar streak. — No growth or barely visible, better on milk agar. Fermenta- 
tion tubes. — Acid in all sugars, commonly closed arm growth, no gas. Bouil- 
lon. Sometimes no growth, commonly slight sediment. Milk. — Acid, promptly 

curdled without gas, no digestion. Potato. — Thin, transparent or no growth. 
Grows better at 20° than at 37°. Facultative anaerobe. Variety A has very 
minute colony. Milk sometimes curdled in 6 hours. Variety B. has dense 
surface colony. Variety C is more anaerobic. Variety D never curdles milk. 

LIQUEFYING BACTERIA. 
I. No Acid in Sugars. 

B. lactis chroma turn Conn. 

Lemon-yellow. — Morphology. — Size 3 X 1.5m.* Chains and spores, no cap- 
sule. Gelatine colony. — Threads in liquefying pit, nucleus with coarse gran- 
ules. Gelatine stab.— Deep, dry pit, later liquefaction. Agar streak. — Lux- 
uriant, moist yellow. Bouillon. Sediment, turbidity, pellicle. Milk. — Alka- 
line, curdling, digestion. Potato. — Luxuriant, dry, wrinkled, yellow. Grows 
at 20° and 37°C. Aerobe. 
B. lactis arborescens II. 

Morphology. — Rods with square ends. Size 2-4X1-1. 8m.* Long chains, 
spores, no capsule, Gram stain negative. Gelatine colony. — Felted fibers on 
liquefying disc. Gelatine stab. — Arborescent needle growth, infundibuliform, 
folded scum. Agar streak. — Spreading, filamentous, cottony. Fermentation 
tubes. Dextrose and saccharose said to be acid, lactose not. Closed arm 



223 

growth, no gas. Bouillon. — Sediment, flaky turbidity, scum. Milk. — Alkaline, 

curdled, digested. Potato. — Luxuriant, cottony. Grows at 20° and 37°C. 

Aerobe. 

B. lactis filiformis. 

Differs from above species in lack of arborescence in gelatine and in slimy 
growth on potato. 
B. lactis truncatum. 

Curled colonies. Morphology. — Size 1.2-2.5 X.7-lm.* Long chains, spores, 
no capsules. Gelatine colony. — Opaque, proteus or curled, % inch in diameter. 
Gelatine stab. — Liquefaction, stratiform, tough, white skin. Agar streak. — ■ 
Luxuriant, rough, irregular, whitish-yellow. Bouillon. — Felted scum, no tur- 
bidity or sediment. Milk. — Alkaline, curdling, digestion, scum. Potato. — 
Luxuriant, white, velvety. Grows at 20° and 37 C C. Aerobe. 
B. lactis michiganii Conn . 

Morphology. — Size 1.8 X. 9m.* Chains, spores, Gram stain negative. Gela- 
tine colony. — Rapid liquefaction, cloudy. Gelatine stab. — Liquefaction com- 
plete in 3 days, infundibuliform. Agar streak. — Spreading, thick, wrinkled, 
opaque. Fermentation tubes. — No acid, gas, or closed arm growth. Bouillon. 
— Sediment, turbidity, wrinkled pellicle. Milk. — Alkaline, curdled, digested. 
Potato. — Luxuriant, filiform, thick, alveolate, gray-brown. Grows better at 
37° than at 20°C. Aerobe. 
B. lactis genevnm Conn. 

Morphology. — Size 3.8 X 1.4m.* Spores, no chains, Gram stain positive. Gel- 
atine colony. — Smooth liquid mass or cloudy. Gelatine stab. — Needle growth, 
stratiform, liquefaction. Agar streak. — Spreading, thin, smooth, whitish. Fer- 
mentation tubes. — No acid or gas, usually closed arm growth. Bouillon. — 
Sediment, turbidity, pellicle. Milk. — alkaline, curdled, digested. Potato. — ■ 
Spreading, smooth, opaque, cream-colored. Grows at 20° and 37°C. Facul- 
tative anaerobe. 
B. lactis erythrogenes Grotenfelt. 

Morphology. — Size 1.2X.9-lm.* Spores, capsule, no chains. Gram stain 
positive. Gelatine colony. — Round, raised, smooth, entire, translucent, yellow- 
ish. Gelatine stab. — Begins to liquefy in 3 days, stratiform. Agar streak. — 
Filiform, raised, smooth, pink. — Fermentation tubes. — No acid or gas, closed 
arm growth in dextrose, and saccharose not in lactose. Bouillon. — Membran- 
ous pellicle, turbidity, flocculent sediment. Milk. — No change in reaction, 
curdling and digestion in 10 days. Potato. — Luxuriant white. Grows at 20° 
and 37°C. Facultative anaerobe. Several varieties. 
B. lactis nibrum. 

Morphology. — Sixe 2-4 X. 9m.* Chains, no spores or capsules. Gelatine 
colony. — Bead-form, granular edge, .7 mm. in diameter. Gelatine stab. — 
Stratiform, clear liquid with scum. Agar streak. — Luxuriant, wrinkled, dull 
orange or pink. — Bouillon. — Sediment, no pellicle or turbidity. Milk. — Alka- 
line, curdling after several days, digestion. Potato. — Glistening, smooth, pink. 
Grows at 20° and 37 °C. A variety is orange rather than pink. 
B. lactis burn" Conn. 

Reddish bitter-milk organism. Morphology. — Size 1-3 X. 7m.* No chains, 
spores or Gram stain. Gelatine colony. — Surface in liquefying area 1-3 mm. 
in diameter. Gelatine stab. — Begins to liquefy in 4 days, infundibuliform. 
Agar streak. — Luxuriant, smooth, lobed, reddish. Fermentation tubes. — No 
acid, gas or closed arm growth. Bouillon. — Turbidity, no sediment or pellicle. 
Milk. — Acid, not curdled or digested. Potato. — No. growth. Grows at 20°, 
not at 37°. Aerobe. 
B. lactis citronis Conn. 

Lemon-yellow, no spores. Morphology. — Size IX. 6m.* Chains, no capsule. 
Gelatine colony. — Small pits with nucleus and lighter outer zone. Gelatine 



224 

stab. — Crateriform liquefaction with dense sediment. Agar streak. — Luxur- 
iant, thick, folded, greenish-yellow. Bouillon.— Turbidity, sediment. Milk — 
Alkaline, digested, sometimes curdled. Potato. — Thick, smooth, pink, or 
lemon-yellow. Grows at 20° and 37°C. Aerobe. 
B. lactis niinutissimiim. 

Slender, orange. Morphology —Size 1.5X.4m.* Long chains, no spores. 
Gelatine colony. — Branching on surface, burr-like below, rays into gelatine 
Gelatine stab. — Begins to liquefy in 2 days, infundibuliform or crateriform, 
yellow sediment. Agar streak. — Luxuriant, spreading orange. Bouillon. — 
Sediment, turbidity, pellicle. Milk. — Alkaline, thick, dark-colored. Potato. — 
Luxuriant, deep orange. Grows better at 20° than at 37°C. Aerobe. 
B. laotis niarshalli Conn. 

Yellow, slimy milk. Morphology.— Size 1.2 X. 3m.* No chains, spores, cap- 
sule nor Gram stain. Gelatine colony. — Slowly liquefying, granular, becom- 
ing irregular and slimy. Gelatine stab. — Begins to liquefy in 2 or 3 days, 
infundibuliform. Not acid. Agar streak.— Luxuriant, viscous, filiform, white 
or gray. Fermentation tubes. — No acid, e:as or closed arm growth. Bouillon. 
—Sediment, turbidity, pellicle. Milkl — Alkaline, digested, not curdled. Pota- 
to. — Luxuriant, filiform, smooth, lemon-yellow. Grows at 20° and 37°C. 
Aerobe. 
B. lactis limbiiriyii Conn. 

Morphology. — Size 1.5-3 X. 5m.* No chains or spores. Gelatine colony. — 
Round, brownish, 1 mm. in diameter, after 6 days yellow disc in cloudy liquid. 
Gelatine stab.— Needle and surface growth, after 6 days liquefaction. Agar 
streak. — Luxuriant, smooth, glistening, dirty yellow. Fermentation tubes.— 
No acid, probably no gas. Bouillon. — Turbidity, no pellicle. Milk. — No change 
in reaction, no curdling, digestion. Potato.— Scanty, yellow, glistening. 
B. lactis lutenm Zimmermann. 

Morphology. — Rod, no chains. Size 1.2X.8m.* No spores or capsule, Gram 
stain positive. Gelatine colony.— Dense center, clear liquid, slow liquefac- 
tion. Gelatine stab.— Slow liquefaction, crateriform. Agar streak.— Luxur- 
iant, filiform, raised, rugose. Fermentation tubes. — No gas acid or closed arm 
growth. Bouillon. — Sediment, turbidity, membranous pellicle.. Milk — Alka- 
line, no other change. Potato.— Luxuriant, spreading, thick, opaque. Grows 
at 20° and 37°C. Aerobe. 
B. lactis ashtonii Conn. 

Morphology. Size 1.2-3 X 1.2m.* No chains, spores or capsule. Gram stain 
irregular. Gelatine colony.— Slow liquefying pit, cloudy, yellowish. Gela- 
tine stab. — Needle growth, napiform liquefaction in 3 days. Agar streak. — 
Filiform, raised, smooth, yellow, viscous. Fermentation tubes. — Closed arm 
growth, no acid or gas. Bouillon. — Sediment, turbidity, pellicle. Milk. — 
Alkaline, curdled, digested. Potato.— Filiform, raised, smooth, yellow. Grows 
better at 20° than at 37 °C. Facultative anaerobe. 
B. lactis album Conn. 

Morphology. — Rods, no chains. Size l-3X.7-.9m.* No spores or capsules. 
Gram stain positive. Gelatine colony. — Slow liquefaction, not characteristic. 
Gelatine stab. — Liquefaction in 3 days, napiform and stratiform. Agar streak. 
— Filiform, raised, smooth, opaque, viscous. Fermentation tubes. — No acid, 
gas or closed arm growth. Bouillon. — Sediment, turbidity, pellicle. Milk. — 
Alkaline, curdled, sometimes digested. Potato.— Abundant, spreading convex, 
brown. Grows well at 20° and 37°C. Aerobe. 

II. Acid in Dextrose or Other Sugars. 
B. lactis musci. 

Morphology.— Long filaments of rods 3Xlm. Central spores. Gram stain 
positive. Gelatine colony.— Myceloid, branching, radiating, white, velvety. 



225 

Gelatine stab. — Arborescent needle growth, then wrinkled surface. Agar 
streak. — Luxuriant, thin, white, wrinkled. Fermentation tubes. — No gas, acid 
and closed arm variable. Bouillon. — Sediment, turbidity, pellicle. Milk. — 
Curdling,amphoteric, digestion. Potato. — Luxuriant, thin, whitish. Grows at 
20° and 37°C. Aerobe. 
B. lactis cretaceum Conn. 

Morphology. — Size 3-5 X 1.4m.* Spores, no chains or capsules. Gram stain 
positive. Gelatine colony. — Not characteristic, slowly liquefying. Gelatine 
stab. — No needle growth, liquefaction in 1 day, stratiform. Agar streak. — 
Filiform, raised, smooth, cretaceous. Fermentation tubes. — Acid and closed 
arm growth in dextrose and saccharose, no acid or lactose. No gas. Bouil- 
lon. — Sediment, slight turbidity and pellicle. Milk. — Alkaline, curdled, di- 
gested. Potato. — Spreading, raised, smooth, cretaceous, white. Grows at 20° 
and 37°C. Facultative anaerobe. 
B. lactis lobatum Conn. 

Orange, acid liquefier. Morphology. — Size .8-1 X. 5m.* No chains, spores 
or capsules. Gram stain positive. Gelatine colony. — Round, raised, smooth, 
homogenous, sometimes yellowish. Gelatine stab. — Slow liquefaction, sac- 
cate then stratiform, liquid cloudy. Agar streak. — Smooth, raised, thin. Fer- 
mentation tubes. — Acid in all sugars, closed arm growth, no gas. Bouillon. — 
Sediment, turbidity, pellicle. Milk. — Acid, not curdled, digested. Potato. — 
Thick, opaque. Grows well at 20°, poorly at 37°C. Facultative anaerobe. 
B. lactis cloacae Conn. 

Morphology. — Size .7-.8X.5m.* Capsule, no chains or spores. Gram stain 
negative. Gelatine colony. — Round, thick, smooth, homogeneous, 1 mm. in 
diameter. Gelatine stab. — Dry pit, later liquefies, infundibuliform. Agar 
streak. — Narrow, raised, smooth, opaque. Fermentation tubes. — Acid, gas 
and closed arm growth in all sugars. Bouillon. — Sediment, turbidity, no pel- 
licle. Milk. — Acid, curdling, no digestion. Potato. — Scanty, white. Grows 
better at 20° than at 37°C. Aerobe. 
B. lactis liquaerogenes Conn. 

Morphology. — Size 1-1.6 X. 7m.* No chains, spores or Gram stain. Gelatine 
colony. — Rapid liquefaction, not characteristic. Gelatine stab. — Liquefaction 
from 2nd. to 9th. days. Agar streak.- — Moderate, spreading, thin, smooth, 
white. Fermentation tubes. — Acid, gas and closed arm growth in dextrose 
and saccharose, no acid or gas in lactose. Bouillon. — Sediment, turbidity, 
pellicle. Milk. — No change of reaction, curdled, digested. Potato. — Moderate, 
spreading, thin, white. Grows at 20° and 37°C. Facultative anaerobe. 
B. visco-fucatum Harrison and Barlow. 

Slimy milk, blue pigment. Morphology. — Size 1-1.8 X. 6-. 9m.* Capsule, no 
long chains or spores. Gram stain positive. Gelatine colony. — Slimy, yellow- 
ish-green crystals. Gelatine stab. — Liquefaction in 10 days, crateriform, inky 
liquid. Agar streak. — Slow, smooth, viscous. Fermentation tubes. — Probably 
acid without gas. Bouillon. — Sediment, turbidity, no pellicle, slimy. Milk. — 
Acid, curdled and digested. Potato. — Luxuriant, yellowish-white, slimy. 
Grows at 20° and 37°C. Aerobe. 
B. lactis brevis Conn. 

Morphology. — Size .7-.9X.5-.6m.* No chains, spores or capsules. Gram 
stain irregular. Gelatine colony. — Round, thin, lobed, whitish. Gelatine stab. 
— Liquefies in 1 or 2 days, stratiform. Agar streak. — Smooth, white, moder- 
ate. Fermentation tubes. — Acid in all sugars, usually closed arm growth, no 
gas. Bouillon.— Sediment, no turbidity or pellicle. Milk. — Acid, curdled, 
partly digested. Potato. — Barely visible, thin, white. Grows at 20° and 37°C. 
Aerobe. 
B. lactis fluorescens Conn. 

Morphology. — Size 1.4-1.5 X. 8-. 9m.* No chains, spores, capsule or Gram 
stain. Gelatine colony. — Slow, lace-like, dense center. Gelatine stab. — 



226 

Needle growth, stratiform, liquefaction in one day. Agar streak. — Filiform, 
translucent, smooth, white, green fluorescence. Fermentation tubes. — No gas 
or closed arm growth, acid in dextrose and saccharose. Bouillon. — Sediment, 
turbidity, pellicle. Milk. — Alkaline, curdled at 20 C C, digestion. Potato. — 
Filiform, raised, white. Grows at 20°, poorly at 37°C. Aerobe. 
B. lactis plicatum Conn. 

Non-acid, white, liquefying. Morphology. — Size 3-5 X. 8-. 9m.* Long chains, 
no spores or capsules. Gram stain irregular. Gelatine colony. — Slow, fold- 
ing. Gelatine stab. — Needle growth, beginning to liquefy in one day, infundi- 
buliform. Agar streak. — Filiform, thick, smooth, opaque. Fermentation tubes. 
All sugars slightly acid, no gas or closed arm growth. Bouillon. — Sediment, 
turbidity, no pellicle. Milk. — Alkaline, curdled, digested. Potato. — Spreading, 
thick, mottled, wrinkled, white. Grows at 20° and 37°C. Aerobe. 
B. lactis gorinii Conn. 

Morphology. — Size 1.5-2.5 Xlm.* Rods with square ends. No chains or 
spores. Gram stain positive. Gelatine colony. — Slow, large pit, mottled clus- 
ters. Gelatine stab. — Begins to liquefy in 2 days, infundibuliform. Agar 
streak. — Spreading, raised, opaque, white, viscous. Fermentation tubes. — 
Acid in dextrose and saccharose not in lactose, no gas or closed arm growth. 
Bouillon. — Sediment, turbidity, pellicle. Milk. — Strongly alkaline, curdled, 
digested. Potato. — Spreading, thick, opaque, moist. Grows at 20° and 37°C. 
Aerobe. Three varieties differing in acid relations. 
B. lactis magnum Conn. 

Morphology. — Size 3 X 1.5m.* Chains, no spores or capsules. Gram stain 
positive. Gelatine colony. — Fairly rapid, may be filamentous, ciliated edge. 
Gelatine stab. — Needle growth, stratiform, liquefaction begins in 1-3 days. 
Agar streak. — Filiform or spreading thick, punctate, white. Fermentation 
tubes. — No gas or closed arm growth, acid in dextrose only. Bouillon.- — Sed- 
iment, turbidity, pellicle. Milk. — Alkaline, curdled, digested into brownish 
liquid. Potato. — Spreading, thick, contoured, white. Grows at 20° and 37 °C. 
Aerobe. 
B. lactis flocculus Conn. 

Acid, non-curdling, liquefying. Morphology. — Size 1-2 Xlm.* No chains 
or spores. Gram stain positive. Gelatine colony. — Slow, lobate or moruloid. 
Gelatine stab. — Needle and surface growth. Agar streak. — Filiform, raised, 
smooth, white. Fermentation tubes. — Acid in dextrose only, no gas or closed 
arm growth. Bouillon. — Sediment, turbidity, pellicle. Milk. — Acid, not curd- 
led or digested. Potato. — Spreading, thin, contoured, white. Grows better 
at 20° than at 37 °C. Aerobe. 

THE GENUS PSEUDOMONAS. 
I. Non-Liquefying. 

P. lactis middletownii Conn. 

Morphology. — Size 1.4X.7-.9m.* No chains, spores, capsules or Gram stain. 
Gelatine colony. — Round, raised, gyrose, entire. On litmus gelatine coarsely 
granular. Gelatine stab. — Dry pit, needle growth. Agar streak. — Filiform or 
spreading, smooth, thin, gray-white. Fermentation tubes. — Closed arm growth 
and gas in all sugars, no acid. Bouillon. — Sediment, turbidity, pellicle. Milk. 
Acid, curdled after several days, digested. Potato. — Luxuriant, spreading, 
thick. Grows at 20°, barely at 37°C. Aerobe or facultative anaerobe. 
P. fluorescens aurea Weigmann. 

Morphology. — Size 2.5X.9m.* Short chains, no spores, capsules or Gram 
stain. Gelatine colony. — Round, raised, contoured, grumose, brownish-red. 
Gelatine stab.— Filiform needle growth, raised surface. Agar streak. — Fili- 
form, smooth, thin, yellowish. Fermentation tubes. — No acid, gas or closed 



227 

arm growth. Bouillon. — Red sediment, ring pellicle, turbidity. Milk.— Alka- 
line or no change in reaction. No other action. Potato. — Filiform, raised, 
brownish-yellow. Grows at 20° and 37°C. Aerobe. A variety turns gelatine 
and milk green. 

P. lactis estenii. Conn. 

Smoky fluorescence, common in milk. Morphology. — Size .8-1.2 X. 4m.* No 
chains, spores, capsules, or Gram stain. Gelatine colony. — Round, smooth, 
capitate, cream-white. Gelatine stab. — Filiform needle growth, raised, dry 
surface. Agar streak. — Filiform, raised, smooth, translucent, slightly viscous. 
Fermentation tubes. — No acid, gas, or closed arm growth. Bouillon. — Sedi- 
ment, turbidity, no pellicle. Milk. — No action. Potato.— Filiform, thin, smooth, 
gray. Grows at 20° and 37°C. Aerobe. 
P. lactis flliformis Conn. 

Morphology. — Size 2.5-3.5X.8-.9m.* No capsules, Gram stain negative, 
spores in long chains, one flagellum. Gelatine colony. — Round, convex, en- 
tire, yellowish. Gelatine stab. — Filiform needle growth, flat surface. Agar 
streak. — Filiform, raised, smooth, yellowish. Fermentation tubes. — No gas 
or closed arm growth, acid in dextrose and saccharose. Bouillon. — Sediment, 
ring pellicle, turbidity. Milk. — Acid, no other change. Potato. — Beaded, thick, 
punctate. Grows better at 20° than at 37°C. Aerobe. 
P. pseudotuberculosis Klein. 

Morphology. — Size 1. 2-1. 8 X. 4-. 5m.* Rod. Long chains. Gram stain posi- 
tive. No spores or capsules. Gelatine colony. — White surface, granular, no 
gas. Agar streak. — Like B. coli, but less luxuriant. Fermentation tubes. — 
Probably no acid or gas. Bouillon. — Turbidity, pellicle no sediment. Milk. — 
No action. Potato. — Thin, crenate, brownish. Found in London milk. 
P. lactis viridis Conn. 

Morphology. — Size .9-1 X.4-.5m.* No capsule, chains or Gram stain. Spores. 
Gelatine colony. — Round, raised, smooth, entire, yellow. Gelatine stab. — 
Needle growth with raised surface. Gelatine turned green. Agar streak. — 
Filiform, raised, translucent, white. Fermentation tubes. — No acid, gas or 
closed arm growth, except acid in dextrose. Bouillon. — Sediment, turbidity, 
no pellicle. Milk. — Slightly acid, no other change. Potato. — Filiform, thin, 
moist, smooth. Grows at 20° and 37°C. Facultative anaerobe. 
P. sapolactica Eicholz. - 

Morphology. — Size .8-1.7 X. 7-. 8m.* No chains, spores, capsules or Gram 
stain. Gelatine colony. — Round, raised, entire, gray. Gelatine stab. — Filiform 
needle growth, flat surface. Agar streak. — Filiform, thick, opaque, white. 
Fermentation tubes. — No acid, gas or closed arm growth, except acid in dex- 
trose. Bouillon. — Sediment, turbidity, ring pellicle. Milk. — Alkaline after a 
few days, no other change. — Potato. — Slight, linear, thin. Grows better at 37° 
than at 20°C. Aerobe. Variety A. produces acid in all sugars and curdles 
milk. 

II. LIQUEFYING. 
P. lactis anana Conn. 

Morphology. — Size .8-1.2 X. 5m. Chains, no spores, capsules or Gram stain. 
Gelatine colony. — Rapid, granular pit. Gelatine stab. — Rapid, infundibuli- 
form or stratiform. Agar streak. — Spreading flat, creamish or brown. Fer- 
mentation tubes. — No acid or gas, usually no closed arm growth. Bouillon. — 
Sediment, turbidity, no pellicle. Milk. — Curdled without change in reaction., 
sometimes greenish. Potato. — Luxuriant, spreading, convex, brown. Grows 
at 20° and 37°C. Aerobe. 
P. lactis eurotas Conn. 

Morphology. — Size .9-1. 5 X. 3m.* No chains, spores, capsules or Gram stain. 
Gelatine colony. — Round, convex, smooth, punctate, entire. Gelatine stab.— 



228 

Slow, stratiform. Agar streak. — Luxuriant, linear, flat, gray. Fermentation 
tubes.— Alkaline, closed arm growth, no gas. Bouillon.— Sediment, turbidity, 
flocculent pellicle. Milk.— Alkaline, curdled, completely digested. Potato.— 
Luxuriant, linear, brown. Grows at 20° and 37 °C. Facultative anaerobe. 
P. lactis nigra Gorini. 

Forms black pigment. Morphology.— Size 2-3.5 Xlm.* No chains, spores, 
capsules or Gram stain. Gelatine colony.— Slow, pit with irregular center 
Gelatine stab.— Liquefaction in 12 hours infundibuliform. Agar streak — 
Filiform, raised, rugose, opaque. Fermentation tubes. — No acid or gas, slight 
closed arm growth. Bouillon.— Sediment, turbidity, wrinkled pellicle. Milk.— 
Acid, curdled, digested. Potato.— Luxuriant, spreading, grayish-brown. Grows 
at 20° and 37°C. Aerobe. 
P. lactis contorta Conn. 

Polypiform, monotrich. Morphology.— Size 1-5 X. 8m.* Spores, single flag- 
ellum. Gelatine colony.— Slow, pit at first umbonate. Lobed on litmus gela- 
tine. Gelatine stab.— Filiform needle growth, flat surface becoming dry pit 
Agar streak.— Moderate, filiform, smooth, . opaque. Fermentation tubes.— 
Closed arm growth, no acid or gas. Bouillon.— Sediment, turbidity, granular 
pellicle. Milk.— Alkaline, not curdled. Potato.— Luxuriant, filiform, opaque. 
Grows better at 20° than at 37°C. Facultative anaerobe. 
P. lactis minuta Conn. 

Morphology.— Size .6-.8X.3m.* Very short rod. No chains, spores or cap- 
sules. Gram stain positive. Gelatine colony.— Round, smooth, raised, entire, 
later liquefying. Gelatine stab.— Slow, crateriform. Agar streak.— Luxuriant, 
filiform, porcelain white Fermentation tubes.— No acid, gas or closed arm 
growth. Bouillon.— Sediment, slight turbidity, no pellicle. Milk.— Acid, not 
curdled or digested. Potato.— Invisible. Grows at 20° and 37°C. Aerobe. 
P. lactis mina Conn. 

Morphology. — Size 1.4-1. 8 X.6M. Slender rod. No spores, capsules or Gram 
stain. Gelatine colony. — Slowly liquefying or dry pit, dense at bottom. Gela- 
tine stab. — Deep dry pit, no liquefaction. Agar streak. — Luxuriant, filiform, 
raised, smooth, white, moist. Fermentation tubes. — No acid, gas or closed 
arm growth. Bouillon. — Granular sediment, turbidity, membranous pellicle. 
Milk. — Slightly alkaline, no other change. Potato. — Nodose, contoured, gray, 
moist. Grows better at 20° than at 37°C. Aerobe. 
P. lactis robertii Conn. 

Morphology. — Size 2X.7-.9m.* Rods with square ends. No chains, spores 
or capsules. Gram stain positive. Gelatine colony. — Rapid, greenish-orange 
pigment. Gelatine stab. — Rapid, stratiform; clear, yellow liquid. Agar streak. 

Luxuriant, raised, smooth, moist. Fermentation tubes. — Closed arm growth, 

no acid or gas. Bouillon. — Sediment, turbidity, membranous pellicle. Milk. — 
Alkaline, curdled, digested, greenish. Potato. — Moderate, filiform, flat, brown. 
Grows at 20° and 37°C. Facultative anaerobe. 

P. lactis anrea Conn. 

Morphology. — Size 1.4 Xlm.* No chains, spores or capsules. Gram stain 
positive. Gelatine colony. — Slow, dark-ringed, round. Lobed on litmus gela- 
tine. Gelatine stab. — Filiform needle growth. Flat surface, liquefaction jtj 
one day. Agar streak. — Luxuriant, filiform, papillate, lemon yellow. Fer- 
mentation tubes.— No acid, gas or closed arm growth. Bouillon. — Sediment, 
slight turbidity, ring pellicle. Milk. — Alkaline, no other change. Potato. — 
Luxuriant, spreading or beaded. Grows better at 20° than at 37 °C. Aerobe. 

P. lactis aerogenes A. Conn. 

Gas-forming monotrich. Morphology.— Size 1-1.2 X.7-.9m.* No chains, 
spores, capsules or Gram stain. Gelatine colony.— Round, raised or flat, wavy 
edge. On litmus gelatine large, moist, acid. Gelatine stab.— Very slow, beaded 
needle growth, thick rough surface. Agar streak.— Thin, whitish, spreading. 



229 

Fermentation tubes. — Acid, gas and closed arm growth in all sugars. Bouil- 
lon. — Sediment, slight turbidity, pellicle. Milk. — Acid, prompt curdling, slight 
digestion. Potato. — Scanty, thin, white. Grows better at 20° than at 37°C. 
Facultative anaerobe. 
P. fluorescens (Jorini. 

Monotrich. Morphology. — Size 1.2-1.8 X. 7m.* No chains, spores, capsules 
or Gram stain. Gelatine colony. — Translucent, liquefying, granular, cloudy. 
Gelatine stab. — Begins to liquefy in 1 day, infundibuliform. Agar streak.— 
Luxuriant, spreading smooth, opaque. Fermentation tubes. — No gas or closed 
arm growth. Acid only in dextrose. Bouillon. — Sediment, turbidity, no pel- 
licle. Milk. — Alkaline at 20 C C, curdled and digested but not at 37°C, green. 
Potato. — Luxuriant, spreading, thin, white. Grows better at 20° than at 37 °C. 
Facultative anaerobe. 
P. lactis varians Conn 

Common in milk. Morphology. — Size 1-1.4 X 8m.* Chains. No spores, cap- 
sules or Gram stain. Gelatine colony. — Round, flat or umbilicate, rugose, 
brownish. Gelatine stab. — Stratiform or infundibuliform, slow. Agar streak. 
— Filiform, raised, opaque, white. Fermentation tubes. — No gas or closed 
arm growth, usually acid in dextrose only. Bouillon. — Sediment, turbidity, 
membranous pellicle. Milk. — Slightly acid and curdled at 20°C, not at 37°C. 
Potato. — Variable, white to brown. Grows better at 20° than at 37°C. Aerobe. 
Variety A. liquefies rapidly. B. acidif leans presamigenes casei Gorini and P. 
fragariae probably belong here. 
P. lactis grannla Conn. 

Morphology. — Spores, chains, no capsules or Gram stain. Gelatine col- 
ony. — Rapidly liquefying pit, coarsely granular, ciliated margin. Gelatine 
stab. — Spiny needle growth, napiform pit, liquefaction in 1 day. Agar streak. 
— Moderate, raised, filiform, grayish. Fermentation tubes. — Acid in all sugars, 
no gas or closed arm growth. Bouillon. — Sediment, turbidity, membranous 
pellicle. Milk. — Slightly alkaline, no other change. Potato. — No growth. 
Grows well at 37°C, barely at 20°C. Aerobe. 

LOPHOTRICHIC BACILLI. 
B. syncyanns (Erb) Migula. 

Bacillus of blue milk. — Morphology. — Size 1.3-2 X. 5m.* Short chains, spores, 
no capsules, Gram stain irregular, polar tuft of flagella. Gelatine colony.— 
Round, raised, smooth, entire, grayish. Gelatine stab. — Filiform needle growth, 
thin surface, not spreading. Agar streak. — Luxuriant, spreading, smooth, 
thin, white. Fermentation tubes. — No gas or closed arm growth, dextrose 
and saccharose alkaline without change of color, lactose slightly acid and 
blue-black. Bouillon.— Black sediment, turbidity, membranous pellicle. Milk. 
— Alkaline, no curdling, blue after a few days. Potato. — Luxuriant, spreading, 
thick, brownish. Grows at 20° and 37°C. Aerobe. 
B. lactis olivaceus Conn. 

Morphology. — Size 1.5-2X.4m.* No chains, spores, capsules or Gram stain. 
Polar tuft of flagella. Gelatine colony. — Round; convex, entire, smooth, red- 
dish. Gelatine stab. — Needle and surface growth, no liquefaction. Agar 
streak. — Luxuriant, filiform, raised, smooth, greenish. Fermentation tubes. — 
No acid, gas or closed arm growth. Bouillon. — Sediment, turbidity, granular 
pellicle. Milk. — Alkaline, greenish, strong odor, no curdling. Potato. — Luxur- 
iant, filiform, flat, brownish-yellow. Grows at 20° and 37°C. Aerobe. 
B. lactis minutns Conn. 

Morphology. — Sixe .5X.4m.* Short chains, no spores, capsules or Gram 
stain. Polar tuft of flagella. Gelatine colony. — Round, convex, smooth, red. 
Gelatine stab. — Needle growth, no surface. Agar streak, — Filiform, raised, 
smooth, yellow. Fermentation tubes. — No acid or closed arm growth. Bouil- 



230 

Ion. — Sediment, turbidity, no pellicle. Milk. — No action. Potato. — Scanty, 
yellowish. Grows at 20° and 37°C. Aerobe. 
B. lactis molecularis Conn. 

Morphology. — Size 1.4X.7m.* Flagella at both ends. No spores, capsules 
or Gram stain. Gelatine colony. — Opaque bead, smooth, entire, white. Micro- 
scopic dots on litmus gelatine. Gelatine stab. — Filiform needle growth, flat 
surface, no liquefaction. Agar streak. — Filiform, flat, smooth, gray-white. 
Fermentation tubes. — No gas or closed arm growth, acid only in dextrose. 
Bouillon. — Sediment, turbidity, pellicle. Milk. — Alkaline, curdled, no diges- 
tion. Potato. — Scanty, moist, flat, brownish. Grows better at 20° than at 
37°C. Aerobe. 
R. lactis isignii. Conn, 

Morphology. — Rod, sometimes chains, spores, capsules, Gram stain posi- 
tive. One flagellum or a tuft. Gelatine colony. — Rapid liquefaction, not 
characteristic. Gelatine stab. — Liquefies in 2-12 days, saccate or stratiform. 
Agar streak. — Spreading, thin, smooth, white, brown at 37 °C. Fermentation 
tubes. — Acid, gas and closed arm growth in all sugars. Bouillon. — Sediment, 
turbidity, no pellicle. Milk. — Acid, curdled, no digestion. Potato. — Luxuriant, 
thick, smooth, yellowish. Grows at 20° and 37°C. Aerobe. 

II. Liquefying, lophotrichic Bacilli. 

B. lactis fluorescens I. Conn. 

Morphology.— Size . 8-1.6 X.4-.6m.* Rod with 2 or 3 polar flagella. No 
chain, capsules or Gram stain. Spores. Gelatine colony. — Round, gray, 
smooth, liquefying into granular pit. Gelatine stab. — Rapid liquefaction, in- 
fundibuliform, cloudy liquid. Agar streak. — Luxuriant, filiform, raised, gray, 
moist. Fermentation tubes. — No gas or closed arm growth, acid in dextrose 
only. Liquid green. Bouillon. — Sediment, turbidity, no pellicle. Milk. — 
Curdling, digestion, no change in reaction. Potato. — Scanty, filiform, smooth, 
brownish-yellow. Grows at 20° and 37°C. Aerobe. 
B. lactis fluorescens II. Conn. 

Lophotrichic rod, sometimes chains. Size 1-1.4 X. 6-. 9. No spores, capsules 
or Gram stain. Gelatine colony. — Rapid, cloudy pit. Gelatine stab. — Liquefies 
in 3 days, napiform. Agar streak. — Luxuriant, filiform, smooth, white or 
brownish. Fermentation tubes. — No gas or closed arm growth, acid in dex- 
trose only. Bouillon. — Sediment, turbidity, flocculent pellicle. Milk. — Alka- 
line, curdled, digested, green. Potato. — Scanty, flat, brownish. Grows better 
at 20° than at 37 °C. Aerobe or facultative anaerobe. 
B. fluorescens minutissimus. 

Morphology. — Size .5-.7X.5m.* No chains, spores or capsules. Gelatine 
colony. — Smooth, liquefying pit, granular. Gelatine stab. — Stratiform, cloudy 
liquid. Agar streak. — Luxuriant, white, green, fluorescence. Bouillon. — Sedi- 
ment, turbidity, pellicle. Milk. — Curdled, green at top, no digestion. Potato. 
— Luxuriant, white to brownish. Grows at 20° and 37°C. Aerobe. 
B. lactis fluorescens III. Conn. 

Morphology. — Size 1.5-3 X. 5-. 7m.* No chains, spores, capsules or Gram 
stain. Gelatine colony. — Rapid, granular. Gelatine stab. — Liquefies in 2 days, 
stratiform. Agar streak. — Luxuriant, spreading, smooth, gray.brown. Fer- 
mentation tubes. — Liquid usually green, no gas, acid and closed arm growth 
in dextrose and sometimes in lactose. Bouillon. — Sediment, turbidity, pellicle. 
Milk. — Alkaline, curdles, digests. Potato. — Scanty, potato discolored. Grows 
at 20° and 37 C C. Facultative anaerobe. 

B. lactis mornloideus Conn. 

Morphology. — Size 1-1.5 X 1.2m.* No chains, spores or capsules. Gram 
stain irregular. Gelatine colony. — Slow pit, lobed and moruloid. Gelatine 
stab. — Needle growth, stratiform liquefaction never complete. Agar streak. — . 



231 

Filiform, raised, smooth, white. Fermentation tubes. — No gas. Sometimes 
closed arm growth. Acid in dextrose only. Bouillon. — Sediment, turbidity, 
pellicle. Milk. — Acid, curdled, digested. Potato. — Scanty, thin, smooth, moist. 
Grows better at 20° than at 37°C. Facultative anaerobe. 

PERBTRICHIC NON-LIQUEFYING BACILLI. 

I. No Acid in Dextrose or Other Sugars. 

B. lactis nigroferas Conn. 

Black. Morphology. — Size .9-1 X. 9m.* No spores, chains or Gram stain. 
Gelatine colony. — Round, thin, smooth, white, later black. Gelatine stab. — 
Needle and surface growth. Agar streak. — Moderate, smooth, moist, becom- 
ing black. Fermentation tubes. — Closed arm growth, no acid or gas, indigo 
scum. Bouillon. — Sediment, turbidity, black pellicle. Milk. — No change ex- 
cept black scum. Potato. — Thick spreading, moist, blue-black. Grows better 
at 20° than at 37°C. Aerobe. 
B. lactis zenkeri (Hanser) Conn. 

Rhizoid or proteus-like. Morphology. — Size 2-3 Xlm.* Frequently chains, 
no spores or Gram stain. Gelatine colony. — Rhizoid with lateral extensions. 
Gelatine stab. — Needle growth, lobate surface. Agar streak. — Thick, white, 
radiating fibers from ragged edge. Fermentation tubes. — No acid, gas oi» 
closed arm growth. Bouillon. — Sediment, no pellicle, usually no turbidity. 
Milk. — Alkaline, no other change. Potato. — Moderately thick, dirty white or 
brown. Grows better at 37° than at 20°C. Aerobe. 
B. lactis colchesterii Conn. 

Morphology. — Size l-2X.7-.9m.* Short chains, capsule, Gram stain positive, 
no spores. Gelatine colony. — Rhizoid, mold-like. Gelatine stab. — Needle and 
surface growth. Agar streak. — Mold-like, extending under surface. Fermen- 
tation tubes. — No acid, gas or closed arm growth. Bouillon. — Sediment, tur- 
bidity, no pellicle. Milk. — No action. Potato. — Thin, yellow. Grows at 20° 
and 37°C. Aerobe. 
B. lactis nebulns Conn. 

Morphology. — Size .8X.3m.* Chains, motile, no spores or Gram stain. 
Gelatine colony. — Thick, contoured, smooth, yellow. Gelatine stab. — Abundant 
needle growth, transparent surface. Agar streak. — Luxuriant, thick, smooth, 
white. Fermentation tubes. — No acid, gas or closed arm growth. Bouillon.— 
Sediment, turbidity, pellicle. Milk. — No action. Potato. — Thin, scanty, white. 
Grows better at 20° than at 37°C. Aerobe. 

II. Acid in Dextrose or Other Sugars. 

B. lactis citreus Conn. 

No chains or spores. Size .8X.5m.* Gelatine colony. — White, opaque, later 
yellow. Gelatine stab. — Needle growth, lemon-yellow surface. Agar streak. — 
Luxuriant, lemon-yellow, smooth. Fermentation tubes. — Probably acid with- 
out gas. Bouillon. — Sediment, turbidity, pellicle. Milk. — Acid, curdles. Po- 
tato. — Luxuriant, white, then lemon-yellow. Grows at 20° and 37°C. Aerobe. 
B. lactis rnbifaciens Gcmber. 

Red pigment. Morphology. — Size 2-3 X. 7m.* Spores, no chains, capsule or 
Gram stain. Gelatine colony. — Thick, gyrose, white. Gelatine stab. — Needle 
growth villous, spreading surface. Agar streak. — Linear, moderate, white. 
Fermentation tubes. — Acid and closed arm growth, no gas. Bouillon. — Sedi- 
ment, turbidity, ring pellicle. Milk. — Acid, curdled like jelly. Potato. — Thick, 
white. Grows better at 20° than at 37°C. Facultative anaerobe. 

B. lactis snlcatns Conn. 

Morphology. — Size 2-2.5 X. 6m.* Active rod, no chains or spores. Gram 
stain positive. Gelatine colony. — Large, spreading, white, rough. Gelatine 



232 

stab. — Needle growth, thin surface. Agar streak. — Thin, linear, white. Fer- 
mentation tubes. Acid and closed arm growth, no gas. Bouillon. — Sediment, 
no turbidity, or pellicle. Milk. — Acid, not curdled. Potato. — Thin, scanty, 
moist, white. Grows at 20° and 37°C. Facultative anaerobe. B. aromaticus 
lactis Grimm may belong here. 
B. dysenteriae Shiga. 

Suspected but not yet found in milk. Morphology. — Size l-3m.* in length. 
Sometimes short. No chains, spores or Gram stain. Gelatine colony. — Nearly 
same as B. coli communis. Gelatine stab. — Needle growth, slight surface. 
Agar streak. — Luxuriant, uneven, thick, feathery edge. Fermentation tubes. — 
Acid, no gas. Bouillon. — Sediment turbidity, sometimes pellicle. Milk. — Acid, 
later alkaline. Potato. — Luxuriant, rough, thick, yellowish. Grows better at 
37° than at 20°C. Produces indol. Pathogenic. 
B. lactis fragariae (Weig) Conn). 

Morphology. — Size 1.3-1.5 X. 7-. 9m.* No chains, spores or gram stain. Gela- 
tine colony. — Round, thick, entire, smooth, white. Gelatine stab. — Needle 
growth, thin surface. Agar streak. — Scanty, thin, moist, white. Fermenta- 
tion tubes. — No gas or closed arm growth, acid in dextrose only. Bouillon. — 
Sediment, turbidity, pellicle. Milk. — Alkaline, transparent. Potato.— Scanty, 
thin, white. Grows at 20° and 37 °C. Aerobe. 

PBRETRICHIC, LIQUEFYING BACILLI. 
I. Producing Pigment. 

B. prodigiosus (Ehrb.) Flugge. 

Morphology. — Size .5-lX.5m.* Chains, coccoid forms, no spores. Gelatine 
colony. — Round, oval, entire, reddish-brown. Gelatine stab. — Saccate lique- 
faction, reddish pigment. Agar streak. — White, later red. Fermentation 
tubes. — Acid in glucose, gas variable. Bouillon. — Turbidity, red sediment, 
pellicle. Milk. — Acid, curdled, digested. Potato. — Rose-red, moist, becoming 
dark red. Grows best at 20°-25°C. Aerobe. 
B. butyri rubri Stadling and Poda. 

Red spots in butter. Morphology. — Size 1-1.5 X. 7-. 8m.* Chains, no capsule, 
spores or Gram stain. Gelatine colony. — Round or oval, brown or yellow, 
central colony in liquid pit. Gelatine stab. — Needle growth, shallow pit. 
Agar streak. — Luxuriant, opaque, wine-red. Fermentation tubes. — Probably 
acid and gas. Bouillon. — Sediment, turbidity, no pellicle, rose-red near sur- 
face. Milk. — Acid, curdled, cheesy odor, rose-red. Potato. — Luxuriant, car- 
mine. Grows at 20° and 37°C. 
B. lactis citronus Conn. 

Morphology. — Size 1.5 X. 8m.* Capsules, no spores or chains. Gram stain 
positive. Gelatine colony. — Round, convex, smooth, entire, white. Gelatine 
stab. — Liquefies, infundibuliform. Agar streak. — Filiform, flat, smooth, lemon- 
yellow. Fermentation tubes. — Closed arm growth, no gas, acid in lactose 
only. Bouillon. — Sediment, turbidity, no pellicle. Milk. — Acid, curdled, di- 
gested. Potato. — Spreading, thin, lemon-yellow. Grows at 20° and 37°C. 
Facultative anaerobe. 
B. lactis harrisonii Conn. 

Slimy milk, yellow. Morphology. — Irregular. No chains, spores or cap- 
sules. Gram stain positive. Gelatine colony. — Irregular, lobate, slimy, um- 
bonate. Gelatine stab. — Outgrowths from needle track, sinks into pit after 
2 weeks. Agar streak. — Luxuriant, viscous, dull. Fermentation tubes. — 
Apparently no acid or gas. Bouillon. — Turbidity, sediment, ring pellicle. 
Milk. — Alkaline, not curdled or digested. Potato. — Luxuriant, spreading, in- 
tensely yellow. Grows at 20° and 37°C. Aerobe. 



233 

B. lactis fluorescens IV Conn. 

Morphology.— Size 2.5-3.3 X. 9-1. 5m.* Chains, spores, capsule. Gram stain 
positive. Gelatine colony. — Granular, central nucleus, liquefying almost im- 
mediately. Gelatine stab. — Rapid, infundibuliform. Agar streak. — Filiform, 
flat, moist, opaque. Fermentation tubes. — Closed arm growth, no gas, acid in 
dextrose only. Bouillon. — Sediment, t urbidity, pellicle. Milk. — Alkaline, 
curdled, digested. Potato. — Spreading. Grows at 37° and 20 °C. Aerobe. 
Variety A, Gram stain negative, flagella long. 

B. lactis niger (Gtorini) Conn. 

Nearly identical with P. lactis niger Gorini. Morphology. — Size 2-3.5 X. 9m.* 
Long chains, no spores or capsules. Gram stain positive. Gelatine colony.- — 
Slow, pit clear then cloudy. Gelatine stab. — Liquefies in 1-10 days, infundi- 
buliform. Agar streak. — Spreading, thin, opaque, white. Fermentation tubes. 
— Slightly acid, no gas or closed arm growth. Bouillon. — After 3 days sedi- 
ment, turbidity, pellicle. Milk. — Alkaline, curdled, digested. Potato. — 
Spreading, irregular, wrinkled, becoming blue-black. Grows better at 37° 
than at 20°C. Aerobe. 

B. lactis arborescens II. 

Morphology. — Size 1.5-4 X 8m. Gelatine colony. — Filamentous, radiating, 
knotted fibers. Gelatine stab. — Dry pit, later liquefying. Agar streak. — Thin, 
barely visible, white. Fermentation tubes. — No acid, gas or closed arm growth 
Bouillon. — Sediment, turbidity, tough scum. Milk. — No action. Potato.— 
Thin, gray or brown. Grows at 20° and 37°C. Aerobe. 
B. lactis rhizoides Conn. 

Morphology. — Size 3X.8m.* No chains, spores capsules or Gram stain. 
Gelatine colony. — Slow, myceloid. Gelatine stab. — Needle growth, saccate 
liquefaction. Agar streak. — Spreading, thin, white, moist. Fermentation 
tubes. — . .o acid, gas or closed arm growth. Bouillon. — Slightly sediment and 
turbidity, no pellicle. Milk. — No action. Potato. — Scanty, white. Grows bet- 
ter at 20° than at 37°C. Facultative anaerobe. 
B. lactis inycoides Conn. 

Morphology. — Size 1-4 X. 6-1. 2m.* Long chains, spores, no capsule. Gram 
stain positive. Gelatine colony. — Small, burr-like, rhizoid, rapidly liquefy- 
ing. Gelatine stab. — Arborescent needle, crateriform. Agar streak. — Luxur- 
iant, dull, wrinkled, tough. Fermentation tubes. — No acid, gas or closed arm 
growth. Bouillon. — Sediment, turbidity, pellicle. Milk. — Alkaline, curdled, 
digested, yellowish. Potato. — Luxuriant, velvety, white. Grows at 20° and 
37°C. Aerobe or facultative anaerobe. 
B. snbtilis. 

Very common in milk. Morphology. — Size 1.5-4 X.6-1.5m.* Chains, 
spores, no capsule, Gram ssiain positive. Gelatine colony. — Rapid liquefaction, 
irregular granular masses. Gelatine stab. — Liquefies in 1 day. Crateriform, 
later stratiform. Agar streak. — Filiform, spreading, cretaceous, wrinkled. 
Fermentation tubes. — No acid, gas or closed arm growth. Bouillon. — Sedi- 
ment, turbidity, pellicle. Milk. — Alkaline, curdled, digested. Potato. — Spread- 
ing, gray, raised, dry or moist. Grows at 20° and 37 °C. Aerobe. Varieties 
with slow liquefaction and negative Gram stain. 
B. lactis cromwelli Conn. 

Morphology. — Size IX. 6m. Chains, spores, capsule. Gelatine colony. — 
Opaque, pit, lobate, then granulat. Gelatine stab. — Dry crateriform pit, later 
liquefaction. Agar streak. — Luxuriant, white with thin edge. Bouillon. — 
Sediment, turbidity, pellicle, reddish. Milk. — Alkalin, curdled, digested. Po- 
tato. — Moist, slimy, profuse jelly, white or yellowish. Grows at 20° and 37°C. 
Aerobe. 



234 

B. jantlrinns Zopf. 

Morphology. — Size 2-5X.4-5m.* Chains, spores, Gram stain positive. Gel- 
atine colony. — Rapid, membranous surface, sometimes violet. Gelatine stab. 
— Rapid, cloudy, liquid, pellicle, violet. Agar streak. — Luxuriant, white, then 
violet. Fermentation tubes. — Probably no gas or acid. Bouillon. — Becoming 
violet, turbidity, slight pellicle. Milk.— Reaction unchanged or slightly acid. 
Potato. — Needle track violet, dark brown surface. 

II. No pigment or Acid. 

IS. la otis oiroiilans I. and II. 

Morphology. — White circulating bacilli. Chains. Gelatine colony. — Pro- 
truding bead in dry pit, then liquefaction. Gelatine stab. — Slow liquefaction, 
narrow funnel with or without rotating axis. Agar streak. — Luxuriant, thick, 
yellowish. Bouillon. — Sediment, turbidity, pellicle. Milk. — Alkaline or un- 
changed, digests with or without curdling. Potato. — Scanty, thin, watery. 
Grows at 20° and 37°C. Aerobe. 
B. aerolactis Conn. 

Like B. megatherium Du Bary. Morphology. — Size 1-1.2 X.4-.8m.* Spores, 
no chains or capsule. Gram stain negative. Gelatine colony. — Rapid, cloudy, 
sometimes nucleus. Gelatine stab. — Liquefaction in 1-10 days, infundibuli- 
form. Agar streak. — Luxuriant, capitate, gray. Fermentation tubes. — No acid. 
Closed arm growth, gas in dextrose and saccharose. Bouillon. — Sediment, tur- 
bidity, ring pellicle. Milk. — Alkaline or unchanged, curdled, digested. Potato. 
— Spreading, gray, moist. Grows better at 37° than at 20°C. Facultative 
anaerobe. 
B. lactis tetragenes Conn. 

Morphology. — Capsule. No chains, spores or Gram stain. Size 3X.7m.* 
Gelatine colony. — Large, rhizoid or proteus-like, slow. Gelatine stab. — Lique- 
fies in 1-3 days. Stratiform. Agar streak. — Filiform, smooth, gray, moist. 
Fermentation tubes. — No action. Bouillon. — Turbidity, tenacious pellicle, no 
sediment. Milk. — Alkaline or unchanged, curdled, slightly digested. Potato. 
—Luxuriant, thin gray. Grows at 20° and 37°C. Aerobe. 
B. lactis distortus Conn. 

Morphology. — Size 3X.7m. Chains, no spores or capsules. Gram stain 
positive. Gelatine colony. — Slow, granular liquid. Gelatine stab. — Slow, strat- 
iform, cloudy liquid. Agar streak. — Filiform, raised, white, moist. Fermen- 
tation tubes.— No acid, gas or closed arm growth. Bouillon.— Turbidity, thick 
scum, no pellicle. Milk. — Amphoteric or no reaction, curdled, digested. Po- 
tato.— White, folded, dry or pasty. Grows at 20° and 37°C. Aerobe. 
B. lactis gelatinosus Conn. 

Produces jelly-like milk. Morphology. — Size .8X.6m.* No chains, spores, 
capsule or Gram stain. Gelatine colony. — Round, smooth, white, slow. Gela- 
tine stab. — Slow, crateriform, white. Agar streak. — Filiform, raised, smooth, 
brownish. Fermentation tubes. — No acid, gas or closed arm growth. Bouil- 
lon. — Sediment, turbidity, membranous pellicle. Milk. — Acid, curdled, di- 
gested into jelly. Potato. — Moderate, raised, brownish. Grows at 20° and 
37°C. Aerobe. 
B. lactis tenuis (Duel) Conn. 

Morphology. — Size 1.2X.5m. No chains, spores or Gram stain. Gelatine 
colony.— Rapid, not characteristic. Gelatine stab.— Arborescent needle 
growth, stratiform liquefaction. Agar streak.— Luxuriant, umbonate, gray iri- 
descent. Fermentation tubes.— Closed arm growth. Acid and gas in dextrose 
only. Bouillon.— Sediment, turbidity, flocculent pellicle. Milk.— Alkaline, 
digested, curdled. Potato.— Filiform, capitate, gray. Grows at 20° and 37°C. 
Aerobe. Variety A has Gram stain but no action on milk. 



235 

B. lactis plicatus Conn. 

Morphology.— Size 2X.8-1.2m.* No chains or capsule. Gram stain positive, 
central spores. Gelatine colony. — Rapid liquefaction, cloudy pit. Gelatine 
stab. — Liquefies in 1-10 days, white folded scum. Agar streak. — Nodose, ru- 
gose, opaque, white. Fermentation tubes. — No gas or closed arm growth. 
Acid in dextrose. Bouillon. — Granular sediment, turbidity, pellicle. Milk.— 
Alkaline, curdled, digested. Potato. — Luxuriant, diffuse, thin, orange-white. 
Grows better at 37° than at 20°C. Aerobe. 
B. lactis amberis Conn. 

Morphology.— Capsule. No chains or spores. Gram stain positive. Gela- 
tine colony. — Rapid, not characteristic. Gelatine stab. — Liquefaction in 1-6 
days, infundibuliform. Agar streak. — Linear, raised, rugose, yellowish. Fer- 
mentation tubes. — No gas. Slight closed arm growth. Dextrose acid, other 
sugars alkaline. Bouillon. — Sediment, turbidity, no pellicle. Milk. — No reac- 
tion, curdled, digested. Potato. — Linear, raised, yellowish. Grows at 20° and 
37°C. Facultative anaerobe. 

B. mesentericus fuscus Conn. 

Morphology. — No chains. Size 1.2-1.5 X.4-.6m.* Central spores, Gram stain 
positive. Gelatine colony. — Round, convex, entire, brownish-red. Gelatine 
stab. — Slow, napiform. Agar streak. — Spreading, thin, rugose, gray. Fer- 
mentation tubes. — No gas or closed arm growth. Acid in dextrose and sac- 
charose. Bouillon. — Slight turbidity, no sediment or pellicle. Milk. — Alka- 
line, curdled, digested. Potato. — Luxuriant, thin, rugose, brownish-red. 
Grows better at. 37° than at. 20°C. Aerobe. 
B. lactis viniis Conn. 

Morphology. — Size 1-1. 2 X. 6m.* Spores. No chains, capsule or Gram stain. 
Gelatine colony. — Rapid, granular liquid. Gelatine stab. — Needle growth, 
liquefying in 1-8 days. Agar streak. — Scanty, linear, thin, opalescent. Fer- 
mentation tubes. — Acid and closed arm growth, no gas. Bouillon. — Amor- 
phous sediment, turbidity, no pellicle. Milk. — Acid, curdles, digests. Potato. 
— Scanty, linear, thin. Grows better at 20° than at 37 °C. Facultative an- 
aerobe. 
B. lactis prucnii Conn. 

Slimy milk bacillus. Morphology. — Spores, no capsule or Gram stain. Gel- 
atine colony. — Rapid, not characteristic. Gelatine stab. — Liquefies in one day, 
stratiform. Agar streak. — Round, flat, opaque, white, viscous. Fermentation 
tubes. — Acid in dextrose. No gas or closed arm growth. Bouillon. — Viscous 
sediment, turbidity, pellicle. Milk. — Acid, curdled, digested, yellowish. Po- 
tato. — Spreading, thin brownish. Grows at 20° and 37 :C. Anaerobe. 
B. lactis fnngiformis Conn. 

Morphology. — Size 3-3.5 X 1.3m.* No chains. Spores, capsule. Gram stain 
positive. Gelatine colony. — Mold-like fibers, disappearing after 2 days. Gela- 
tine stab. — Begins to liquefy in 2 days but never complete. Agar streak.— 
Filiform, grumose, raised, white. Fermentation tubes. — Closed arm growth, 
no gas, dextrose acid, other sugars alkaline. Bouillon. — Sediment, granular 
pellicle, no turbidity. Milk. — Alkaline, curdles, digests, strong odor. Po- 
tato. — Luxuriant, thick, white, rough. Grows at 20° and 37°C. Facultative 
anaerobe. 

III. No Pigment. Acid in Dextrose and Other Sugars. 

B. lactis cloacae Conn. 

Morphology. — Size 1-1. 3 X. 7m.* No chains or spores. Capsule, Gram stain 
positive. Gelatine colony. — Slow, dense granular pit. Gelatine stab. — Lique- 
faction in 1-6 days, infundibuliform. Agar streak. — Filiform, raised smooth, 
iridescent. Fermentation tubes. — Acid and closed arm growth. Gas in dex- 
trose and saccharose only. Bouillon. — Sediment, turbidity, pellicle. Milk. — 



236 

Acid, curdled, digested. Potato. — Scanty, thin, white. Grows better at 20° 
than at 37°C. Facultative anaerobe. 
B. lsictis cloacae A Conn. 

Morphology. — Size 1.5X.5-.6m.* Chains. No spores, capsule or Gram stain. 
Gelatine colony. — Round, raised grumose, wavy edge. Gelatine stab. — Rapid, 
infundibuliform, much gas. Agar streak. — Filiform, flat, smooth, moist. Fer- 
mentation tubes. — Acid, gas and closed arm growth. Bouillon. — Sediment, 
turbidity, granular pellicle. Milk.- — Acid, curdled, not digested. Potato. — 
Scanty, white. Grows at 20° and 37°C. Facultative anaerobe. 
B. (Proteus) vulgaris (Hauser). 

Morphology. — Size 1.2-4X.6m.* Long chains. No spores, capsule, or Gram 
stain. Gelatine colony. — Irregular amoeboid processes. Gelatine stab. — Be- 
gins to liquefy in 12 hours, saccate. Agar streak. — Luxuriant, moist, slimy. 
Fermentation tubes. — Probably gas, and acid in dextrose. Milk. — Acid, 
curdles, digests. Potato. — Luxuriant, slimy, yellowish-white. 
B. lactis diffusus Conn. 

Morphology. — Motile. Size lX.6-.9m.* No chains. Gelatine colony. — Dif- 
fuse, faint cloud, mold-like. Gelatine stab. — Napiform, pink liquid. Agar 
streak. — Luxuriant, pink, moist, smooth. Fermentation tubes. — Probably acid 
without gas. Bouillon. — Sediment, turbidity, no pellicle, red. Milk. — Acid 
after several days, curdles, no other change. Potato. — Luxuriant, bright pink. 
Grows at 20° and 37°C. Aerobe. 
B. lactis coclileatus Conn. 

Morphology. — Size 1.8-3 X.7-.9m.* No chains, spores or capsule. Gram stain 
positive. Gelatine colony. — Slow, lobed, cochleate. Gelatine stab. — Begins 
to liquefy in 3 days, stratiform. Agar streak. — Linear or spreading, thin, 
moist, white. Fermentation tubes. — No gas or closed arm growth. Acid in 
dextrose and saccharose only. Bouillon. — Sediment, turbidity, no pellicle. 
Milk. — Alkaline, curdled, digested. Potato. — Very scanty, white. — Grows 
better at 37° than at 20°C. Aerobe. 
B. lactis robertii Conn. 

Morphology. — Size 1.5X.5-.8m.* No chains, spores, capsule or Gram stain. 
Gelatine colony. — Slow, dense, white. Gelatine stab. — Slow, stratiform, cloudy 
liquid. Agar streak. — Filiform, smooth, white, contoured. Fermentation 
tubes. Acid in dextrose only, no other change. Bouillon. — Sediment, turbid- 
ity, ring pellicle. Milk. — Acid, curdling no digestion. Potato. — Luxuriant, 
thick, moist, white. Grows better at 20° than at 37 °C. Aerobe. 

ACID GAS PRODUCERS. 
Bacterium aerogenes type. 
B. lactis aerogenes Esch. 

Morphology. — Size 1.4-5 Xl-1.5m.* Sometimes capsule. No chains or spores. 
Gram stain irregular. Gelatine colony. — Thick, round, smooth, moist, some- 
times viscous, 2 mm. in diameter. Gelatine stab. — Needle growth, thick, white 
surface. Agar streak. — Luxuriant, moist, gray. Fermentation tubes. — Acid, 
gas and closed arm growth in all sugars. Bouillon. — Sediment, turbidity, 
usually pellicle. Milk. — Strongly acid, curdles, gas. Potato. — Luxuriant, 
dirty white. Grows better at 37° than at 20°C. Aerobe. No indol. One 
variety produces indol, a second a thick colony, and two others bitter milk. 

The Coli Communis Type. 

B. coli aerogenes Conn. 

Flagellate. Morphology. — Size l-3Xl-1.4m.* No chains, spores or Gram 
stain. Gelatine colony. — Prominent, thick, smooth, moist, large. Gelatine 
stab. — Needle growth, thick white surface. Agar streak. — Filiform, raised, 



237 

smooth, opaque. Fermentation tubes. — Acid, gas and closed arm growth, 
not much gas. Bouillon. — Sediment, turbidity, usually pellicle. Milk.— 
Strongly acid, curdles with gas. Potato. — Luxuriant, white or straw color. 
Grows better at 37° than at 20°C. Aerobe. Indol produced, or sometimes 
not. 

B. coli communis Esch. 

Like the last species, but produces a thinner, umbonate colony on gelatine 
with a granular lobate edge. Indol is produced. B. coli is very common in 
milk on account of the frequent contamination with feces. 
B. coli communis. 

Typical characters. Morphology. — Size 1-1.6 X.4-lm.* No chains, spores, 
capsule or Gram stain. Plagella peretrichic. Gelatine colony. — Thin, spread- 
ing umbonate, smooth center, lobate. Gelatine stab. — Filiform needle growth, 
spreading, moderate surface. Agar streak. — Filiform, raised, smooth, white, 
sometimes lobed. Fermentation tubes. — Acid, gas, and closed arm growth 
in all sugars. Bouillon. — Turbidity, sediment, ring pellicle. Milk. — Acid, 
curdling, no digestion. Potato. — Moderate, smooth, gray-white. Grows better 
at 37° than at 20°C. Aerobe. Indol produced. One variety produces gas in 
dextrose only, and another renders milk slimy. 
P. coli communis Conn. 

Gas-producing Pseudomonas. Morphology. — Size 1-1.5 X. 8-. 9m.* No spores, 
chains, capsule or Gram stain. Gelatine colony. — Round, thick, smooth, auri- 
culate, gray. Gelatine stab. — Filiform, umbonate, bluish surface. Agar 
streak. — Moderate, linear, raised, gray. Fermentation tubes. — Acid, gas and 
closed arm growth. Bouillon. — Sediment, turbidity, flocculent pellicle. Milk. 
— Acid, curdling, no digestion. Potato. — Moderate, thin, spreading. Grows 
better at 20° than at 37°C. Facultative anaerobe. Almost identical with B. 
coli communis except that there is only one flagellum, which is long and 
characteristic. 

In addition to the bacteria which may occur in milk and cause various 
changes in it a number of fungi other than bacteria may gain entrance to 
milk. Of these perhaps Oidium lactis and Torula aniara are most common. 
Brief descriptions of these fungi may be given in this connection. 
Oidium lactis. 

This is the conidial form of a mildew belonging to the same genus with 
the powdery mildew of the grape. It occurs normally in sour milk. Mor- 
phology. — Fruiting hyphae simple, erect, colorless, bearing at the tips chains 
of conidia which germinate to form septate hyphae. Takes ordinary aniline 
stains. The spores or conidia are short cylinders. Gelatine. — Colonies at 
first white points, becoming stellate and finally covering the entire surface 
with a mycelial network. Makes similar growth on agar. 
Torula amara Harrison. 

Morphology. — Oval cells 7.5-10 m.* long, showing vacuolation after a few 
days, budding at smaller end of cell. Singly or in clumps or chains. No 
spores. Wort.— Abundant growth at 25°C. No pellicle. Yeast rings form 
at 37°C. Wort gelatine. — Pin-point colonies becoming round and grayish- 
white in 4 days. Gelatine stab. — Beaded line becoming dense and spiny. 
Surface waxy becoming brown at center. Wort agar. — Rapid, luxuriant. 
Agar. — Glistening, flat. Potato. — In 3 days slightly raised, yellowish growth. 
Milk.— Bitter in 5 or 6 hours, curdled in 10 days, much gas, no butyric acid. 

Extent of Contamination of Milk With Bacteria. 

It has already been stated that milk at the moment of its secretion 
in the normal udder is absolutely free from bacteria. As soon as it 
reaches the milk cistern at the base of the teats, however, it becomes 



238 

contaminated to some extent, usually with bacteria of a comparatively 
harmless type. In the manipulations to which milk is subjected 
during- milking and in handling until it reaches the consumer and 
afterward until it is actually consumed it is continually subjected to 
contamination from outside sources and some of the species of bacteria 
which were present at the time the milk was drawn are continually 
multiplying. For these reasons it is obvious that the number of 
bacteria found in milk will vary enormously according to the age of 
the sample of milk, the temperature under which it has been kept and 
the other conditions to which it has been subjected. 

When all of the sanitary precautions mentioned in chapter VI are 
duly considered and put in practice milk may be drawn and bottled 
or poured into cans in such condition that it contains only a few 
hundred bacteria per cc. The variation in the number of bacteria 
actually found in samples of market milk, however, is enormous. 
Samples of milk which otherwise appear to be in excellent condition 
may contain 50,000 bacteria per cc. and in samples of less satisfactory 
milk the bacterial contamination may vary from this degree up to 
200 million or more per cc. On account of the extremely different 
conditions which prevail on different dairy farms and in the handling 
of milk by the different dealers it is obviously of little value to discuss 
in great detail the extent of bacterial contamination which has been 
found by actual estimates. A few determinations of this sort may be 
cited in order to illustrate the great difference in the extent of bac- 
terial contamination. Thus Park in an investigation which he made 
in a well ventilated and fairly well cleaned barn in which the cows 
were groomed in a satisfactory manner and in which the milkers 
were fairly clean but the straining cloths not satisfactorily cared for 
found the number of bacteria per cc in milk cooled to a temperature 
of 45°F. within two hours after milking was 15,500. After 24 hours 
the number was 21,000 and after 48 hours 76,000. These figures 
were obtained in winter. Under similar conditions in summer the 
number of bacteria per cc. shortly after milking was 30,000, after 24 
hours, 48,000 and after 48 hours 680,000. In the case just cited 
the necessity of sanitary precaution in handling milk was fairly well 
understood. The bacterial contamination, however, in cases where 
no attempt is made to prevent the entrance of bacteria, into milk is 
enormously greater. Thus according to' examinations of milk in St. 
Petersburg the number of bacteria per cc in farm milk was 9,800,000, 
in creamery milk 1,150,000,000 and in milk delivered to ordinary 
customers along the milk route 82,000,000. Similar figures obtained 
for milk furnished to various other European cities show a contami- 
nation ranging from 4,000,000 to 170,000,000 bacteria per cc 

In tests made by Loveland in Middletown, Conn., the number of 
bacteria per cc. in samples of milk ranged from 11,000 to 300,000. 
In a similar examination made by Russell in Madison, Wis., the 
number ranged from 35,000 to 2,000,000. In a number of samples 



239 

of market milk taken in Washington, Boston and New York, bacterial 
contamination has been found as high as 2,500,000 to 600,000,000 per 
c.c. When these enormous figures are compared with those obtained 
from an examination of milk drawn with special precautions by com- 
mercial dairymen who appreciate the necessity of sanitation in regard 
to milk, it is apparent that too much importance cannot be laid upon 
the strict observance of the simple rules which have been shown to 
be effective in preventing the bacterial contamination of milk. It has 
been demonstrated, for example, in numerous instances in large 
dairies furnishing milk to the chief cities of the United States, that 
the number of bacteria per c.c. need not exceed 500 to 1,000 at the 
time the milk is delivered to the consumer. Nevertheless boards of 
health have in no instance insisted upon such a low bacterial content 
in formulating a milk standard. It has been necessary to allow a 
greater bacterial contamination for the practical reason that at present 
not enough dairymen are properly equipped to furnish the necessary 
amount of milk with a bacterial content not exceeding 1,000 per c.c. 
In practice it has been found that milk containing not more than 
10,000 to 50,000 bacteria per c.c. of the ordinary species is a satis- 
factory milk for ordinary use. Milk intended for children should 
contain fewer bacteria and such milk can be obtained in all of our 
large cities. 

Influence of Temperature Upon the Bacterial Content 

of Milk. 

It is well understood in general that cold aids in preserving milk 
for the simple reason that it checks the development of those bacteria 
which produce souring and other changes in the milk. Since it is 
practically impossible to obtain milk absolutely free from bacteria it 
is therefore necessary that cold should be applied to milk at once in 
order to prevent the multiplication of bacteria. The keeping of milk 
is everywhere closely dependent, upon temperature. At high tempera- 
ture milk sours and undergoes other changes rapidly. At moderate tem- 
peratures these changes take place less rapidly, while at a temperature 
of 40 degrees F. the souring and other changes may be postponed for 
a long time. If milk is actually frozen it may be kept indefinitely 
without any appreciable change. 

Conn, Freudenreich and numerous other investigators have care- 
fully studied the influence of temperature upon the keeping property 
of milk. In one experiment, reported by Conn a sample of milk was 
divided into two parts, one of which was maintained at a temperature 
of 50° and the other at 70°F. The number of bacteria per c.c at the 
beginning of the experiment was 46,000. After twelve hours the 
number in the milk kept at 50 degrees F. was 39,000, and in that kept 
at 70°, 249,000. After fifty hours the number of bacteria per c.c. in 
the milk kept at 50 degrees F. was 1,500,000 and in that kept at 
70°, 542,000,000. 



240 

In further tests along this line it was found that in a period of 
twenty-four hours the bacteria ordinarily present in milk will multiply 
only five-fold at a temperature of 50 °F, but 750-fold at a temperature 
of 70 U F. Similarly it was found that milk kept at 95°F. will curdle 
in about 18 hours, at 70 °F. in 48 hours and at 50 °F. not until after 
two weeks or more in many of the samples. 

It might be concluded therefore as indicated by Conn that the keep- 
ing quality of milk is more a matter of temperature than of cleanli- 
ness. In fact milk may be almost indefinitely prevented from souring 
or showing other visible changes merely by the application of cold. 
Nevertheless milk gradually becomes filled with bacteria of a more 
harmful nature than the lactic acid organisms and other bacteria 
which grow at higher temperatures. For this reason, milk kept for 
long periods by means of cold is unfit for use although it may be 
perfectly sweet. 

The application of cold in the preservation of milk may in one 
respect be considered from the same standpoint as the use of preserva- 
tives. The low temperatures serve to prevent the development of the 
bacteria which are already present in the milk and thus mask to the 
consumer the extent of contamination of the milk. In the case of 
badly contaminated milk, therefore, the application of cold may 
simply make it possible to sell milk which would otherwise quickly 
show such visible changes as to render its sale impossible. Never- 
theless refrigeration must be used in -the handling of milk for the 
reason that otherwise all milk would sour too soon for practical pur- 
poses and the high temperature of the air, particularly in summer, 
would permit of the rapid multiplication of the less harmful bacteria, 
which, however, would cause souring and other undesirable changes. 

The Time Factor in the Number of Bacteria in Milk. 

At the temperature of an ordinary living room common milk bac- 
teria will divide every twenty to thirty minutes. By means of a 
simple calculation it is easy to demonstrate that the presence of a 
few hundred bacteria per c.c. in milk at the time it was drawn will 
lead in the course of twenty-four hours, if low temperatures are not 
maintained, to an enormously high number of microorganisms. In 
investigations carried on by Freudenreich it was found that the num- 
ber of bacteria multiplied from 500,000 to 85,000,000 per cu. in. in 
the course of twenty-four hours. Other examples of equally rapid 
multiplication are cited by the same investigator in which the number 
increased steadily from the outstart of the observations. The rapidity 
of multiplication depends in large degree upon the cleanliness which 
is observed in the milking and handling of milk. Any pollution added 
to the milk after it is drawn will obviously tend to increase greatly 
the number of bacteria. Thus in observations made by Park in New 
York upon milk kept at a temperature of 90°F., the number of bac- 
teria per c.c. in good, fresh milk, fair store milk and poor store milk 



241 

was 5,000, 92,000 and 2,600,000 at the outset and 654,000, 6,800,- 
000 and 124,000,000 respectively after eight hours. As already indi- 
cated the rapidity of multiplication is greatly diminished by keeping 
the milk at a low temperature. The intervals between the divisions 
of the micro-organisms are greatly lengthened and some of the species 
are not able to multiply at all on account of the predominance and 
antagonistic influence of other species. 

Antagonism Between Bacteria of Different Species. 

Attention has already been called to the fact that when a consider- 
able number of species of bacteria is present in milk not all of them 
are able to multiply at the same rate. Most species of bacteria thrive 
best on a neutral or slightly alkaline medium. In nearly all milk, 
however, as it comes from the udder, there are a number of lactic acid 
bacteria which soon produce sufficient acidity in the milk to check 
the growth of a number of species of bacteria which do not thrive 
in the presence of acid. Other kinds of antagonism have been noted 
in mixed culture experiments in which several species of bacteria are 
grown in the same medium. In some cases one organism appears to 
produce substances as a result of growth which actually favor the 
growth of other bacteria, while in other cases the changes produced 
in a medium by one species of micro-organism and the toxins or other 
bodies thereby produced antagonize or entirely prevent the growth of 
certain other species of bacteria. The multiplication of bacteria in 
milk, therefore, is never as rapid as would be possible if no unfavor- 
able conditions were present. 

Means of Reducing the ]STumber of Bacteria in Milk. 

In chapter VI attention has been called to those practices in dairy- 
ing which have been found to reduce the number of bacteria as found 
in milk at the time it is delivered to the consumer. It is unnecessary, 
therefore to discuss in detail these means of the bacterial sanitation 
of milk in this connection. The most essential thing is to exercise such 
cleanliness in milking and handling milk as will prevent the contam- 
ination of milk. By the exercise of common sense and intelligence, 
enlightened by modern bacteriological studies of milk it is possible 
to obtain milk with a very slight bacterial contamination and to handle 
and deliver it in such a way that no subsequent contamination takes 
place, and the multiplication of bacteria which were originally present 
is reduced to a minimum. It has been repeatedly stated, however, 
that aseptic milk on a commercial scale is a practical impossibility. 
Some bacteria are always present in the milk as it comes from the 
udder. The dairyman must therefore apply cold at the start in order 
to prevent too rapid multiplication of these organisms. The observ- 
ance of cleanliness, therefore, and the application of cold to milk until 
the time of its delivery are the chief means upon which the dairyman 
must depend in furnishing pure milk to his patrons. 



242 

Growth of Bacteria in Milk. 

It has already been indicated that the majority of bacteria require 
for their rapid growth the presence of certain organic compounds in 
a readily available form. These compounds are found in milk in an 
almost ideal condition at the time when it is drawn from the udder. 
The casein and other albuminous constituents of milk furnish a 
sufficient quantity of protein for the growth of bacteria. Lactose or 
sugar of milk is perhaps the form of sugar which is most readily 
available for the use of bacteria and most easily decomposed and 
otherwise influenced by them. The presence of fat in a low percentage 
is favorable to the growth of many species and this constituent like- 
wise is present in fresh milk in the form of butter fat. Moreover 
milk at the time it is drawn has a neutral or at least only slightly 
acid reaction and in this respect it is therefore a suitable medium 
for the growth of bacteria. These conditions originally present in 
milk as it is drawn from the udder are rapidly changed by the growth 
of the bacteria in it. The reaction of milk soon becomes acid as the 
growth and multiplication of lactic acid bacilli proceed and the per- 
centage of acid in the milk soon reaches a point where many of the 
gas-forming and liquifying bacteria are no longer able to grow. On 
the other hand the lactic acid bacteria are very susceptible to the 
influence of heat and are therefore readily killed by the pasteurization 
of milk. In pasteurized milk, therefore, souring does not take place 
readily and favorable conditions are presented for the growth of such 
gas-forming and putrefactive bacteria as may be present in the milk. 
These highly undesirable changes in pasteurized milk can only be 
prevented by the application of cold. 

Souring of Milk. 

The familiar phenomenon of the souring of milk is one of the results 
of the presence of bacteria in the milk. The souring of milk is so 
well known and takes place after the lapse of a certain time with such 
unfailing regularity that the process is often considered as a natural 
phenomenon in connection with milk. Nevertheless it has been re- 
peatedly shown that milk free from bacteria may be kept in -hermet- 
ically sealed vessels for months wuthout souring and without showing 
any other visible change. The souring of milk is therefore due to the 
presence of a foreign body in it and has been definitely connected with 
the growth and multiplication of lactic acid bacteria which produce 
the ferment necessary to cause the change from the neutral to the acid 
reaction. In the process of souring, milk curdles or becomes semi- 
solid and the percentage of acid gradually increases. The lactic acid 
arises from the prompt decomposition of the milk sugar by the action 
of bacteria. The lactic acid bacteria are undesirable in milk, at least 
in large numbers, if the milk is intended for delivery to the regular 
customers of a milk route for consumption as such. In the manufac- 
ture of butter and cheese, however, these organisms are of the greatest 



243 

utility and are depended upon for the ripening of cream and cheese 
and the production of certain flavors and other changes which are ex- 
pected in butter and cheese. The utilization of lactic acid bacteria in 
the manufacture of butter and cheese, however, is a matter which 
belongs to technical dairying and cannot be further discussed in this 
connection. 

Coagulation of milk is perhaps more properly used to refer to a 
process quite different from that of ordinary curdling. Curdling, as 
we have used it in this connection, denotes the change from a fluid 
to a semi-solid condition in milk as the result of the growth of lactic 
acid bacteria. This is one form of fermentation, but coagulation 
proper is a condtion which is brought about in milk during the manu- 
facture of cheese and is due to a coagulation fermentation in which 
the curd differs in composition and in physical structure from the 
curdled semi-solid mass in milk soured simply by the action of lactic 
acid bacteria. The coagulation of milk may be brought about by the 
use of rennet. This ferment is commonly used, as is well known, in 
the coagulation of milk in the manufacture of cheese. Rennet con- 
tains a specfic ferment known as rennin and is chiefly obtained from 
the mucous membrane of the fourth or true digestive stomach of 
calves. It is also present in the pancreas of man and a number of 
other animals. 

Conn and others have shown that certain bacteria may produce 
during their growth a ferment which shows all of the essential char- 
acteristics of rennet. These bacteria may possess at the same time a 
ferment which digests the milk. In some instances only one of the fer- 
ments is present. Coagulation may be brought about first, after which 
digestion takes place, or the digestion of milk may occur without pre- 
vious coagulation. Duclaux and others isolated a ferment to which 
the name "casease" was given, which is produced by bacteria and 
which brings about the digestion of the casein in milk after it has 
been coagulated by the action of the enzyme producing bacteria. 

The bacteria which produce the rennet-ferment and casease are the 
most important forms of enzyme-producing bacteria found in milk. 
Casease as present in milk causes the digestion of the casein already 
formed by the rennet enzyme and in its action and composition so 
far as it has been determined differs very little from pepsin and tryp- 
sin. The enzyme-producing bacteria are not so common in milk as 
many other forms and when present may coagulate milk rapidly 
without the formation of acid. They are thus readily distinguished 
from the lactic acid bacteria which develop a considerable percentage 
of acid in connection with the curdling of milk. If the liquifying or 
digesting bacteria are present in milk the milk must be looked upon 
with some suspicion. Bacteria which digest casein also liquify gela- 
tine and their presence is therefore readily detected by the use of 
gelatine cultures. 

Swithinbank calls attention to the fact that milk /may occasionally 
coagulate spontaneously. This was first demonstrated by Levy, who 



244 

showed that a slight coagulation may be observed in nearly all sterile 
samples of milk which are allowed to stand for a long time. The 
casein of the milk however is not all coagulated. In fact in most 
such samples of milk only small fragments of the casein are coagulated. 

Abnormal Fermentations. 

As contrasted with the kinds of fermentation already described as 
occurring in milk there are a number of others which produce striking 
changes in the color or appearance of the milk and are universally re- 
ferred to as abnormal fermentations. The essential physical features 
of these fermentations have been referred to in chapter II on abnormal 
milk and are mentioned here merly from the standpoint of bacteriol- 
ogy. Red milk as distinguished from bloody milk is due to the pres- 
ence of micrococcus prodigiosUsS. This organism grows quite rapidly 
upon the surface of milk, causing red spots. The milk serum is not 
affected. One or more other organisms have also been described as 
causing a red color in milk. 

Yellow milk is due to the action of a number of bacteria which pro- 
duce a yellow pigment, particularly the Bacillus synxanthus of Ada- 
metz. These bacteria act quite differently upon milk, some of them 
causing a pronounced yellow color rapidly, while others appear to 
produce a coagulation of the milk, after which the yellow color 
appears. 

Blue milk was formerly mentioned quite frequently as a pathological 
condition observed in the examination of milk. Ii was referred by 
Hiippe to the action of Bacillus cyanogenes. Milk affected with this 
bacillus does not differ in other respects from ordinary milk. After a 
varying length of time, however, small blue spots appear on the surface 
of the milk and these spots may coalesce to form a complete covering 
to the sample of milk. 

Slimy or ropy milk is sometimes observed, usually as the result of 
insufficient cleansing of milk utensils. The peculiar fermentation of 
milk resulting in the production of slimy threads is commonly due to 
the action of certain micrococci and bacilli, a number of which have 
been mentioned by different investigators. These include at least 
twelve species mentioned by Adamete, G-uillebeau, Schmidt, Conn and 
others and are described in the list of milk bacteria given above. The 
condition known as slimy milk is commonly caused by Bacillus ladis 
viscosus but may also be due to a micrococcus in certain instances. 

Occasionally milk shows a bitter flavor which is not due to the con- 
sumption by the cows of bitter weeds but, to micro-organisms which 
gain entrance to the milk. The bitter flavor is caused by certain micro- 
cocci or bacteria, the chief organisms being different in different cases. 
In one instance cited by Conn the bitter flavor was produced by bac- 
teria which were present in the udder of one cow in a herd and 
disappeared as soon as this cow's milk was excluded. 



245 

An organism was isolated by Weigmann from milk which frothed, 
had a soapy feeling and flavor and appeared to be otherwise abnormal. 
The organism in question is described in the list of milk bacteria 
above. 

Various other abnormal conditions of milk not due to bacteria are 
described in more detail in Chapter II. 

The Significance of Streptococci in Milk. 

In the sanitary crusade which has been carried on in recent years 
for a pure milk supply for large cities, it has usually been considered 
by health officers and others interested in this problem that the pres- 
ence of streptococci in milk indicate a pathological condition of the 
udder of the cow. The ordinary streptococci found in milk have been 
generally supposed to be associated with the presence of pus cells in 
milk and have therefore been held as a sufficient ground for casting 
serious suspicion upon the condition of the milk in which they are 
found. 

Recent investigations regarding the kind and number of bacteria 
found in the milk ducts and teat canals show that these micro-organ- 
isms may be readily divided into two groups, one producing lactic 
acid fermentation and containing the two common types of bacillus 
lactis acidi and bacillus lactis aerogenes and the other producing no 
acid but causing the appearance of various odors and flavors or putre- 
factive changes in the milk. The common lactic acid organisms, how- 
ever, have been shown by Holling, Kruse, Heinemann and Harris to 
exist under a variety of forms, particularly that of the bacillus and 
also of the streptococcus. These investigators have cast considerable 
doubt upon the importance previously attributed to the presence of 
streptococci in milk. It is certain that pathogenic streptococci may 
be found in milk at times, particularly in cases of contagious mam- 
mitis or garget. In cases where these organisms are to be recognized 
in the milk, however, the disease can also be diagnosed by an exam- 
ination of the cow. Harris and others call attention to the fact that 
bacteriological methods do not differentiate with certainty between 
pathogenic and non-pathogenic streptococci. The investigators just 
mentioned are all decidedly of the opinion that the common lactic 
acid bacteria may exist under the form of streptococci and that there- 
fore the presence of streptococci in milk may not indicate any abnormal 
contamination. The whole question of the significance of streptococci 
in milk is therefore thrown open for further investigation. 

Comparative Growth of Different Species of Bacteria in Milk. 

The subject of the relative rate of growth of different species of 
bacteria in milk and the suitability of milk as a medium for the growth 
of these different kinds of bacteria has been referred to above. A num- 
ber of investigators have made a study of this point. By adding litmus 



246 

and milk sugar to the ordinary gelatine medium Conn was able to 
identify about thirty species of bacteria which were mostly found in 
milk a few hours old. This method suffers somewhat from the fact 
that the gelatine plates have to be kept three to five days or longer 
and when liquefying bacteria are present a complete liquefaction of 
the gelatine takes place before the colonies of the bacteria can be 
identified. Among the most common species found in comparatively 
fresh milk were two forms of bacillus lactis acidi, bacillus lactis aero- 
genes, several species of streptococcus, bacteria producing rapid or 
slow liquefaction and two species of sarcina. In samples taken after 
the milk had been allowed to stand for eighteen hours or more bacillus 
lactis acidi was found to have increased with marvellous rapidity, 
sometimes constituting 99% of the total number of bacteria. The 
other species decreased both relatively and absolutely and the liquefy- 
ing bacteria often disappeared entirely. 

In -272 samples of milk studied by Bergey immediately after the 
milk had been drawn three types of micro-organisms were most fre*- 
quently observed, viz: streptococcus., staphylococcus and a bacillus 
of the pseudo-diphtheria type. The streptococci were present in 
largest numbers sometimes to the extent of 5,000 per c.c. In milk 
examined by the same investigator after it had been allowed to stand 
for some time and had been subjected to the possibility of infection 
from the air, milk vessels, and other sources, another set of micro- 
organisms was found to have been added. This included chiefly 
putrefactive bacteria which produced an alkaline reaction in milk 
cultures and liquefied gelatine. Many of these organisms were such 
as are commonly found in water and probably gained entrance to the 
milk through the water used in washing milk vessels. Attention is 
called to the fact that these organisms are not pathogenic but they 
belong to a group which produces putrefaction in milk with the 
possible formation of poisonous ptomaines. 

Methods of Bacteriological Examination of Milk. 

It is impossible within the limits of the present volume to describe 
in detail the methods of preparation of the numerous culture media 
which have been used by bacteriologists in the study of bacteria in 
milk and of the great variety of stains which have been employed to 
assist in the identification of bacterial species. It is assumed that 
the milk inspector who makes bacteriological examinations of milk is 
familiar with the technique of these matters and in this connection 
only such points will be discussed as have immediate bearing upon the 
application of the bacteriology to the study of milk. In the biblio- 
graphical list titles will be found of original articles and other sources 
in which information can be found regarding the preparation of 
culture media and stains and the use of bacteriological apparatus. 

Culture media. — In the extensive and long continued investigations 
which Conn and his associates have made upon milk bacteria the isola- 



247 

tion of the various species of milk bacteria has been for the most part 
accomplished by the use of litmus gelatine. In Conn's experience 
this medium has given a better differentiation of colonies than any 
other solid media commonly used for the purpose. As soon as bacterial 
cultures have been thus isolated and purified they are re-inoculated 
upon agar streaks and after about two days' growth on this medium 
are again inoculated into various other culture media at the disposal 
of the bacteriologist. Cbnn has found it desirable to use fresh cul- 
tures on agar streaks to determine the morphology, using older cul- 
tures if necessary to study the formation of spores. The motility of 
bacteria is ordinarily studied by Conn in a hanging drop of bouillon 
culture of twelve to twenty-four hours' growth. The flagella are 
commonly studied by the same investigator by removing a portion of 
the hanging drop with a platinum loop and spreading it over the sur- 
face of solidified agar which is then incubated for twelve hours at a 
temperature of 37 degrees C, after which a small quantity is removed 
and stained by the Loeffler method. 

In Conn's study of milk bacteria preference is expressed for the 
use of Liebig's beef extract in the place of chopped beef in the prepar- 
ation of bouillon, gelatine and agar. Tests in fermentation tubes are 
made with dextrose, lactose and saccharose, one per cent of these 
sugars being added to ordinary bouillon. The milk which Conn uses 
for cultures is skimmed and sterilized by boiling for ten to fifteen 
minutes on three successive days. Potato cultures are made by cutting 
plugs from large potatoes, slicing them obliquely, soaking them over 
night in running water and sterilizing them in tubes in an autoclave. 
The peptone-agar culture recommended by Conn is prepared by using 
10 grains of dry peptone, 5 grams common salt, 5 grams Liebig's beef 
extract and 30 grams of milk sugar in 500 liters of water. Conn's 
sugar gelatine contains 13 grams of peptone, 150 grams gelatine, 7 
grams Lieibg's beef extract and 30 grams of milk sugar in a thousand 
c.c. of water. 

Quantative examination of milk. — The technique of the bacterio- 
logical examination of milk is discussed in unusual detail in the excel- 
lent volume by Swithinbank and Newman on the Bacteriology of 
Milk. Some of the methods which these investigators have found to be 
of greatest practical value are briefly summarized in the following 
paragraphs : 

The apparatus required for the bacteriological study of milk include 
ordinary pipettes, dropping pipettes accurately calibrated, .an abund- 
ant supply of test tubes, conical flasks marked at a point indicating 
49 cc. and Petri dishes. In making a dilution of milk taken from a 
sample selected for examination, the procedure as described by Swith- 
iubank and others is comparatively simple. Using a sterilized pipette 
one c.c of the milk is added to a test tube containing 9 c.c. of sterile 
water. The milk and water are thoroughly mixed and this constitutes 
the primary dilution in the proportion of 1 to 10. If one cc. of the 



248 

primary dilution be added to a flask containing 49 cc. of sterile 
water the total content will obviously be 50 cc, containing one-tenth 
of the original quantity of milk, or in a dilution of 1 to 500. If a 
dilution of 1 to 1000 is desired it is easily obtained by transferring 
one cc. of the primory dilution to a second tube containing 9 cc. of 
water and again one cc. of this mixture to a third tube. Whatever 
the extent of final dilution which is adopted it will be found desirable 
in estimating the bacteria of milk to inoculate three Petri dishes from 
each sample, using 1 drop, 2 drops and 4 drops respectively. If the 
sample of milk contains a relatively small number of bacteria, it 
may be desirable to use ten drops for inoculation. 

The transfer from the final dilution to the Petri dish may be made 
as follows : aspirate a small quantity of liquid from the final dilution 
into a calibrated dropping pipette, add the desired quantity of the 
diluted milk to the tubes of gelatine being careful to prevent any other 
bacterial contamination, roll the gelatine tubes in the hand until the 
diluted milk is thoroughly mixed with the gelatine, then pour the 
gelatine into the Petri dish carefully, so as to obtain a level surface 
and keep the dish level until solidification takes place. For ordinary 
milk bacteria the temperature of the living room is the best at which 
to maintain the Petri dishes of gelatine during the incubation of the 
bacteria. The colonies of bacteria on the gelatine in the Petri dishes 
are to be counted on the second, third and fourth days and these 
counts should include not only the total number of colonies but also the 
number of colonies which produce liquefaction of gelatine. After 
the number of bacteria in the minute quantity of diluted milk placed 
in the Petri dish has been determined by an examination of the cul- 
ture a simple mathematical calculation will give the number of bac- 
teria per cc. of the milk. Thus if one drop of a dilution at the rate 
of 1 in 500 be taken and 75 organisms are found on the plate, the 
number of bacteria per cc. of this milk is 750,000, for one drop 
equals .05 or 1-20 cc and 75X20X500=750,000. 

For staining milk bacteria the stains usually recommended include 
carbolfuchsin, methylene-blue, Loeffler's alkaline blue and gentian- 
violet. Por compound staining and for special purposes it is of course 
necessary to use the Gram method, particularly as modified by Mcolle, 
the ZiehKNeelsen method,, Pitfield's method or McCorie's method for 
staining flagella, Moeller's method for staining spores and MacCon- 
key's for staining capsules. 

Choice of culture media. — The standard liquid media for cultiva- 
tion of milk bacteria are bouillon and milk, and the standard solid 
media gelatine and agar, the latter being necessary for use in the 
cultivation of organisms requiring a blood heat. Gelatine may in 
fact be considered as a solid bouillon and gelatinized milk may be 
prepared as a solid form of milk media. The cultures uniformly 
used by Conn in the study of all milk bacteria include gelatine colony, 
gelatine stab, agar streak, fermentation tubes, bouillon, milk and 



249 

potato. These are sufficient for all ordinary milk bacteria and no 
addition will be necessary to this list of cultures except in the case of 
special bacteria for which special culture methods are required. Thus 
glycerine and potato are commonly used for the tubercle bacillus and 
carbolized media for the typhoid bacillus. Bacteria which produce 
cholera nearly always grow well on potato. The variety of media which 
have been used for the cultivation of bacteria is almost unlimited, but 
the standard culture media are all that the milk inspector will have 
occasion to use for practical purposes. 

Qualitative examination of milk. — In making a rapid differentiation 
between the various groups of bacteria which may be found in milk it 
is necessary to transfer minute quantities of each sample of milk to 
several kinds of nutrient media.. Thus the aerobic organisms may be 
separated by using simultaneously gelatine, agar and blood serum. 
The growth of bacteria upon these culture media should enable the 
milk inspector to detect the presence of ordinary milk bacteria as well 
as the bacillus of diphtheria, tuberculosis, pseudo-tuberculosis, dysen- 
tery, coli bacillus and streptococci. The cultivation of anaerobic 
bacteria require special apparatus since they must be grown in a 
vacuum or in hydrogen. Fjor this purpose various tubes have been 
devised by Vignal, Roux, Esmarck, Fraenkel, Pasteur and others. 

Bacteriological examination of air. — The milk inspector may find 
it desirable to determine the extent of bacterial contamination of the 
air of stables in forming a general opinion as to the sanitary condition 
of the premises. For this purpose perhaps the best results are obtained 
by exposing plates of nutrient agar or gelatine for a short time in 
different parts of the stable according to the method proposed by 
Koch. Several other methods have been proposed in which measured 
quantities of air are drawn into air tubes for the purpose of sampling 
to determine the bacterial content. 

Bacterial examination of water. — If any suspicion is entertained 
regarding the quality of the water supply used for watering stock or 
washing the milk utensils, chemical tests may be applied such as are 
used in detecting various foreign bodies in milk, as discussed in 
chapter XL Bacteriological examinations may be made in essentially 
the same manner as the inspector would proceed in the quantative 
examination of milk. In most instances satisfactory results will be 
obtained if five gelatine plates are inoculated with quantities of the 
water to be examined ranging from .1 to .5 c.c. respectively. If 
desired agar plates may be used at the same time for the purpose of 
rendering easy the qualitative determination of the bacterial content 
of the water. 

The Boston method of bacteriological examination of milk. — The 
routine of bacteriological examination of milk adopted by the Boston 
Board of Health may well be given in this connection as an example 
of a system that has been well considered and carefully worked out. 



250 

This method is based on the consensus of opinions given by the bac- 
teriologists of fifteen prominent laboratories engaged in the examina- 
tion of milk. The method has been well described by Slack. 

The samples of milk for examination are transferred to test tubes 
by the use of large sterile pipettes, and a copper carrying case with 
double walls and felt inside has been adopted for the transportation 
of the samples in the test tubes. During the transportation of these 
samples the milk is maintained at a temperature of 34 degrees F. 
For routine work a dilution of 1 to 10,000 has been found most satis- 
factory. In the examination of fresh samples from individual cows 
or from milk known to be relatively pure the sample is diluted only 
100 times and for milk which is suspected of being excessively con- 
taminated a dilution of 1 to 1,000,000 has been adopted. The water 
used for dilution is kept in square 8 oz. bottles, which have been found 
very convenient to handle and economical of space. The medium used 
for bacteriological examination is agar-agar. The addition of lactose 
or litmus to the medium has apparently not given any special ad- 
vantage in the tests which were made by the Boston Board of Health. 
Gelatine is not used for the reason that a long time must elapse before 
a report can be made, and difficulty is experienced in keeping it at a 
uniform temperature and preventing liquefaction. In the Boston 
system of milk examination the agar plates are incubated for twenty- 
four hours in a saturated atmosphere at 37 degrees C. 

The counting apparatus as described by Slack is of a very simple 
construction. A circle 4% inches in diameter and divided into 10 
equal segments is cut into the surface of an ordinary school slate, 
after which the lines are filled with red lead. If the slate becomes 
gray with use it may be blackened by rubbing with vaseline. The 
Petri dish is uncovered and placed bottom down over the circle, after 
which it is covered with a wooden box . open at the bottom, with a 
glass front and four inch circular opening at the top, the wooden 
parts being painted black to avoid refraction of the light, A four 
inch reading glass with a magnification of about two diameters fits 
over the opening of the box and keeps a constant focus, thus leaving 
both hands of the inspector free. 

In Boston the Board of Health condemns milk on account of the 
presence of streptococci if a microscopic examination of the milk 
sediment shows the presence of streptococci or diplococci or cocci; 
and if the agar plate inoculated from the same sample shows apparent 
colonies of streptococci in excess of 100,000 per c.c. and broth cul- 
tures from these colonies show streptococci alone or in excess of other 
bacteria. 



251 



CHAPTER XIII. 

TKANSMTSSION OF INFECTIOUS DISEASES BY MILK. 

Milk may be an important agent in the transmission of disease to 
man. Pathogenic bacteria may gain entrance to milk by direct secre- 
tion with the milk from diseased cows; from wounds, sores, or ulcers 
on the teats or other parts of the body of cows; from dust or other 
filth which may fall into the milk or become lodged on milk utensils ; 
from diseased milkers; or from infected water used in washing cans 
and other utensils. As indicated in the discussion of the bacteriology 
of milk, bacteria find an unusually favorable nutrient medium in milk. 
After once getting into the milk they multiply rapidly, retaining 
their virulence completely. If, therefore, milk is allowed to become 
contaminated with disease germs it is a dangerous food for man and 
other animals, particularly calves and pigs. 

It is apparent that milk may become infected with and may carry 
not only diseases which affect cattle and other animals, but also many 
human diseases, such as typhoid and scarlet fevers, diphtheria, septic 
processes, etc. The most important animal diseases which may be 
transmitted to man through milk are tuberculosis, foot-andrmouth 
disease, cowpox, anthrax, actinomycosis, septicemia, enteritis, etc. 

The whole movement in favor of improved methods for managing 
dairy herds and in handling milk is based on the recognized danger 
to human health from an uncontrolled milk supply. If disease could 
not be transmitted in milk the most urgent reason for inspecting milk 
would be removed. It has been definitely proved, however, that a 
number of diseases may be transmitted to man in the milk of diseased 
cows or by means of milk which has become contaminated after re- 
moval from the cow. In this connection the only point about which 
there is essential difference of opinion is the actual extent, and fre- 
quency of such transmission. The question thus raised must be 
answered somewhat differently in the case of different diseases, but in 
general, there is more likelihood of underestimating than of over- 
estimating the danger from using milk which contains pathogenic 
bacteria. 

Tuberculosis. — The prevalence and almost universal distribution of 
tuberculosis among cattle places this disease at the head of the list of 
infections which may be transmitted by milk. The fact that tubercle 
bacilli occur in milk has been known and the possibility of such 
occurrence was pointed out by Virchow and Koch in 1882. Since the 
first proof of the secretion of tubercle bacilli in the milk of tuberculous 
cows there has been much controversy concerning the conditions under 
which milk is infectious. 



252 

The direct proof of the infectiousness of cow's milk for man could 
be obtained only by means of feeding or inoculation experiments with 
man. Obviously such experiments are oul of the question. Wo must 
depend, therefore, on accidentaJ infection through wounds, cases of 
intestinal tuberculosis in children and adults, and other clinical evi 
deuce. The infectiousness of milk may best be demonstrated l>,y 
feeding or inoculation experiments with calves, pigs or laboratory 
animals, 

In attacking this problem the Erst question u> bo determined is 
whether the mills of tuberculous cows contains tubercle bacilli ami, 
if not, whether the conditions under which they arc not found in flic 
mills may be defined, Both parts of this question must be answered 
in the negative. The mills of tuberculous cows docs not always eon- 
tain the bacilli of the disease. In general the bacilli arc not found in 
the milk in llie early stages of the disease. When tlie udder is affected 
llic milk is almost always infections. Likewise in advanced Stages of 

the disease and in cases of generalized tuberculosis the mills usually 

contains the bacilli. In milk from (lie same cow they may be absent, 

one dav and present the next. Even if the milk in the early 

Stages of the disease be considered safe, it is impossible to predict 
when if will become dangerous. In fact no general statement can be 

made as to the time when it is Likely to become infected. The milk 

Of all tuberculous cows mUSl therefore be condemned as abnormal 
and dangerous even if no physical symptoms of the disease have ap- 
peared audi diagnosis is made entirely by the aid of tuberculin. So 

long as the tubercles in affected cows are walled in or surrounded by 
a oapsule oi' connective tissue there are no bacilli in the blood or milk 
except in cases of mamillary tuberculosis. Whenever ;i tubercle 
breaks down, however, bacilli escape into the blood and from there 
readily gain cut, ranee to the milk. As the tubercles become more 

numerous and more generally distributed throughout the body, indi- 
vidual tubercles break down more frequently and the milk is infectious 
a greater part of the time. This point, may be fairly summed up by 
saying that in the early stages of the disease, or so long as physical 
symptoms are absent the milk is usually I'vcc from tubercle bacilli, 
while in cases of mammary I iihercu losis or in advanced Stages with 
physical symptoms the bacilli arc likely to be louiid in the milk. For 
present, purposes it is iiuiiecessa v\ to give details of the results olv- 
lained by the numerous investigators who have busied themselves with 

this problem. The experiments of Bollinger, Ostertag, Ernst, Martin, 
Woodhead, Bank, Johne, Mohler, Baumgarten, et al., indicate that 

in I .'» per cent to 70 per cent of tuberculous cows I he milk is infectious. 

At the Storrs Experiment Station, Phelps kept, I tuberculous cows 

under observation for I years and their milk was fed bO calves without 

previous pasteurization^ ami for periods of i.2-18 months. During the 

first two years only one case o\' tuberculosis developed among the 

calves. The results obtained during tin' next IS mouths were quite 



253 

different. During this time 5 calves were fed the mills of the same 
rows and all . r » became tuberculous. Ai the beginning of the fourth 
year of the test 3 of the cows began to decline but the other appeared 
to be in good health. This experiment is mentioned merely as one 
illustrative example among hundreds. Phelps concludes from it that 
the danger of the spread of tuberculosis through the mill* of infected 
cows is not its great as generally supposed. This conclusion, however, 
is unjustified except when restricted to the early stages of the disease. 

Marshal] in Michigan found that pigs could be fatally infected by 
feeding them milk containing tubercle bacilli. Pigs and calves were 
similarly infected by Russell. Mohler curried on an extensive series 
of feeding and inoculation experiments with the milk of 66 tuberculous 
cows. These cows gave a reaction to tuberculin but did nol have an 
affection of the udder. In 21 per cent of the cows, however, the milk 
was infectious. The number of bacilli in the milk of these cows 
varied from day today without assignable cause. Ravenel round that 
the milk of cows which merely reacted to tuberculin but showed no 
physical signs of disease may be virulenl for guinea pigs in L5 percenl 
of cases. 

Rabinowitsch and Kempner obtained similar results. On the other 
hand Ostertag succeeded in infecting guinea pigs with the milk of 

Only one out of 50 reacting cows which showed no clinical evidence of 

tuberculosis. Ostertag therefore considers the milk of such cows 
harmless. These results in turn are interpreted quite differently by 
oilier invesi iL'-iil.ors who iisseri, that Larger samples should be taken of 
such milk since the bacilli may be very scarce, and may be entirely 
absent in one small sample. 

Ostertag found that the alarming increase of tuberculosis among 
hogs in northern Germany was connected with the increase in the 
number of creameries and was caused by the raw by-products of the 
creamery, especially the separator slime. Separator milk and butter 

milk also Serve to spread the disease unions; calves. I (, :i!k found llial, 

nil the hogs lO\ by creamery owners and milk dealers were i nberculous, 
Borgeaud observed a regular enzootic among pigs ^^l on separator 
milk. No further cnscs :i|)pe;ired after the practice of boiling milk 
before feeding was adopted. Similar conditions have been observed 
by other investigators. The point under discussion may be summed 
up iii the statement thai the milk of tuberculous cows is the chief 

source of tuberculosis in calves and pigs. 

In the previous discussion we have, shown lhal the milk of luher 

culous cow's may, and, in a large percentage of cases, does contain 

tubercle bacilli ; and lhal, l.he bacilli arc virulent and produce Inbereii 
losis in calves, pigs, and laboratory animals when i nocii hied or i\\<\ 

with such material. Tuberculous milk serves to spread tuberculosis 
among live stock and is therefore unfit to feed to calves, pigs, and 
other animals. We have now to discuss the question whether if is 
also dangerous to man. 



254 

This question has been answered in every possible way. Koch 
says that the danger is so slight that milk may be disregarded as a 
source of human tuberculosis. In his opinion milk almost never 
transmits the disease to man. At the other extreme we have von 
Behring who asserts that "the milk fed to infants is the chief cause 
of tuberculosis." The great mass of students hold opinions between 
these extremes. 

The question of intertransmissibility of bovine and human tuber- 
culosis has been unnecessarily complicated by connection with the 
question of the unity or duality of tuberculosis. From the time of 
Koch's discovery of the tubercle bacillus until 1898 it was generally 
considered that there is but one species of this organism affecting 
man, cattle and other domesticated animals. During this time it was 
firmly believed that tuberculous human attendants were a source of 
danger to cows and similarly that the disease might be conveyed to 
man in the milk of tuberculous cows. In 1898 Theobald Smith pub- 
lished some experiments indicating a racial difference among tubercle 
bacilli. A human and a bovine form were recognized. In 1901 Koch 
announced his belief in two distinct forms of tubercle bacilli. Koch's 
position that human tuberculosis could not be transmitted to cattle 
and that tuberculous milk was not dangerous to man was immediately 
attacked by other investigators who were present at the London Con- 
gress on Tuberculosis. Since that date literally thousands of articles 
have appeared in nearly all of which Koch's views have been strongly 
combated. The majority of investigators hold that human and bovine 
tubercle bacilli although differing in virulence and sometimes in ap- 
pearance, are nevertheless of the same species and show merely varietal 
differences. 

In 1903-1907 Raw published the results of his observations to the 
effect that there are two distinct kinds of tuberculosis and that man 
is susceptible to both. Raw made a study of more than 4,000 cases 
of pulmonary tuberculosis in man in which the lesions were strictly 
confined to the lungs in all except 14 cases. The lungs were some- 
times found to be infected simultaneously with two kinds of tubercle 
bacilli, one more virulent than the other. Raw believes that most 
cases of pulmonary consumption in man are acquired by infection 
from other human tuberculous patients, while primary intestinal 
tuberculosis and other tuberculous affections of the serous membranes 
in children are probably of bovine origin, produced by milk and not 
related to human tuberculosis. On account of the fact that the two 
forms of tuberculosis are rarely seen together it has been assumed that 
they are mutually antagonistic to each other, and that bovine tuber- 
culosis may confer immunity to the human form of the disease. 

According to the announcement of the German commission for the 
study of tuberculosis these investigators have found that 2 distinct 
forms of tubercle bacilli, the human and, the bovine, must be recog- 
nized. It is held that in a majority of cases human tuberculosis is 



255 

contracted from man. Quite recently Smith published a summary of 
his investigations along this line for the last 5 years in which he pre- 
sents fresh evidence of essential differences between human and 
bovine tubercle bacilli. The two types of bacilli were obtained from 
human mesenteric glands and showed characteristic differences in 
morphology and virulence. Smith believes that mammals other than 
cattle are probably infected from cattle or man or perhaps from both 
sources. The idea that there are 2 forms of the disease both of which 
may affect man appears therefore to rest on a firm basis at present. 

That the milk of tuberculous cows may carry infection to man is 
thus admitted by all investigators of this problem. Koch and his 
disciples say that such transmission is rare but they concede the fact 
of transmission. It is therefore quite unnecessary that practical 
measures for the santary control of milk should be held in abeyance 
until the technical question of the unity or duality of tuberculosis 
is settled. 

We may now proceed to a brief discussion of the methods of infec- 
tion of man with tuberculosis. In the first place it is generally 
acknowledged that tuberculous milk is not always harmful for adult 
man. The alimentary tract of the adult appears to be somewhat pro- 
tected against infection with tubercle bacilli. If, however, the mucous 
membranes are abraded or weakened by disease, infection may readily 
take place. The case is quite different with children. The human 
infant like the young of most animals is exceedingly susceptible to 
infection through the intestinal walls, which readily permit the pas- 
sage of tubercle bacilli. Statistics, were collected for the city of 
Stettin which showed that for the first year of life the mortality was 
473 per 1,000, while at the age of 10 years it was 3 per 1,000, in 
other words the mortality was about 160 times as great for the first 
as for the tenth year of life. 

The percentage of tuberculous infection in children follows a curve 
which corresponds with the importance of milk in the diet. Accord- 
ing to statistics collected by Heubner the following percentages are 
observed: Under 3 months of age per cent, at 3-6 months 3,6 per 
cent, at 9 months 11.8 per cent, at 1 year 26 per cent. Thereafter 
the infection decreases to 5 per cent at the age of 7-10 years. These 
figures indicate the close connection between milk and the tuberculous 
infection in children. In a study of 300 cases of the infantile form 
of tuberculosis known as tabes mesenterica Raw found that every 
case occurred in a child which had been nourished for a considerable 
period on cow's milk and not one in a child which had been nursed 
exclusively at the mother's breast. 

In weighing the evidence in this problem it should always be re- 
membered as pointed out by von Behring that tuberculosis is a slow 
infection. It may be months or years before the disease is recog- 
nizable. By that time the circumstances surrounding infection may 
be entirely forgotten. The length of the period during which the 



256 

disease remains latent depends upon the virulence of the virus, the 
number of bacilli introduced and the acquired susceptibility of the 
person due to colds, unfavorable weather, poor food, insanitary hous- 
ing, overwork, etc. If as a result of these secondary causes operating 
upon the adult person pulmonary consumption appears, this may be 
due to an infection received from milk in early infancy. In fact in 
von Behring's opinion this is true in a majority of cases. 

Again, attention should be called to the great difficulty of identify- 
ing cases of primary intestinal tuberculosis in children. The opin 
ions of different investigators are much at variance on this point 
Moreover, the percentage of intestinal tuberculosis and tabes mesen- 
terica in children apparently varies in different countries. In Eng- 
land tabes mesenterica. constitutes 46 per cent of the total cases oi 
tuberculosis for the first year of life and 36 per cent under 5 years 
of age. In Paris, Berlin, New York, Chicago, and Boston, however, 
the percentage of abdominal tuberculosis is much smaller. But since 
many investigators are willing to admit that it is practically impos- 
sible to identify the primary lesion these statistics are not very reli 
able. They fail to show the method of infection for the reason that 
the tubercle bacilli may cause no lesion at the point of entrance, but 
perhaps in some organ quite remote from that point. Ravenel and 
others have shown th^ when dogs are given tubercle bacilli with their 
food the bacilli may be found in the chyle and mesenteric gland? 
within 1 to 4 hours. The gastroenteric mucous lining is readily per- 
meable in young animals. Disse found that the mucous lininjr of the 
stomach is thin in newborn animals and becomes thicker with age. 

At the Ohio Experiment Station Thorne collected the opinions of 
339 practicing physicians on the infectiousness of the milk of tuber- 
culous cows. The majority of these men had observed cases of infan- 
tile tuberculosis the source of which was apparently milk. Host of 
the physicians with country practice thought that the milk from one 
cow was safer for infants while most of the city physicians preferred 
mixed milk. This difference of opinion is doubtless due to difference 
in environment, Recently the Bureau of Animal Industry has in- 
fected monkeys by feeding them tuberculous milk. On account of 
the close zoological relationship between man and monkeys this exper 
iinent in itself furnishes almost direct proof of the transmissibility of 
tuberculosis from cattle to man. 

What then shall be done with the milk of tuberculous cows ? An 
unprejudiced review of this question indicates clearly that such milk 
may transmit tuberculosis to infants and to pigs, calves, and other 
domesticated animals. In thickly settled localities 50 per cent or 
more of the dairy cows may be tuberculous and the extent of tubercu- 
losis among adult human beings is estimated by different authors 
between 40 per cent and 95 per cent, These percentages may be much 
reduced in both animals and man by preventing infection through the 
alimentary tract. It is therefore a highly important matter to pre- 



257 

vent the use of raw tuberculous milk as food for man or domesticated 
animals. 

It is hardly necessary to call attention to the fact that the more 
numerous the bacilli in milk the greater the likelihood of infection. 
The danger is especially great in cases where an infant drinks the 
milk of a single tuberculous cow for a long period. In the mixed 
milk of a herd the tuberculous milk, if such cows are present, is more 
or less diluted with the milk of healthy cows. The danger of infec- 
tion is thereby diminished for any given individual who drinks the 
mixed milk but is presented to a much larger number of persons, 
among whom susceptible ones may well be found. In advanced cases 
of mammary tuberculosis Ostertag has recently shown that the milk 
\s infectious when diluted to the extent of 1 :1, 000, 000. It is thug 
apparent that one tuberculous cow may render highly infectious the 
milk of a whole dairy or all the milk with which it could possibly 
be mixed. 

Tubercle bacilli do not multiply in milk or at any rate such multi- 
plication is so slight as to be negligible for practical purposes. They 
retain their virulence, however, without noticeable attenuation for 
long periods, much longer than milk will keep. In fact virulent 
tubercle bacilli have frequently been found in butter and cheese. It 
must also be rememberedi that milk may become contaminated with 
tubercle bacilli from tuberculous attendants or from insanitary hand' 
ling. ISTo data are available regarding the frequency of such contam- 
ination. Mohler and Schroeder have shown that the feces of tuber- 
culous cows nearly always contain tubercle bacilli, which may get into 
the milk. 

Foot and mouth disease. — In cases of this disease the milk is nearly 
always virulent. The virus is either secreted with the milk or gains 
entrance into the milk from the vesicles on the teats and udder which 
are ruptured during the process of milking. According to Brown the 
milk presents few abnormal characteristics in the early stages of the 
disease. The specific gravity is somewhat lowered. Within 3 days, 
however, large granular masses of a brownish-yellow color and pus 
corpuscles appear in the milk. The yield of milk is greatly diminished 
during the progress of the disease. 

The milk from cows infected with foot-and-mouth disease is very 
virulent for children and young animals to which it is given in a fresh, 
warm condition. Calves sometimes die quite suddenly as a result of 
sucking cows which are affected with the disease. Fatal effects have 
also followed the feeding of such milk to pigs. Adult man is not so 
readily infected and many cases are known in which the milk has 
been consumed without bad effects. The milk, however, is quite unfit 
for use since numerous epidemics of eczema contagiosa or apthous 
stomatitis have been caused by it. According to Johne many cases of 
"pneumonia" accompanied by eczematous eruptions, and often fatal 
to infants, occurred in localities where foot-and-mouth disease was 



258 

prevalent, Brussenius and Siogel collected data on 16 epidemic out- 
breaks of the disease in man which occurred from 1878-180(5. Nearly 
all cases resulted from drinking unboiled milk. Tn 3 of the outbreaks 
76 deaths occurred. The Gorman Imperial Health Office compiled 
an account of L72 cases in man, 00 of which were due to milk and 1 
to butter. Eertwig and 2 medical friends demonstrated the infectious- 
ness of such milk by drinking it. for a period of 4 days, one quart daily 
each. Within 2 days the symptoms of the disease appeared in the 
form of fever, headache, pains in the legs, and an itching sensation. 
After 5 days the mucous membranes of the mouth became swollen 
and numerous blisters appeared on the tongue, lips, and cheeks. After 
a few days the vesicles ruptured, leaving red, slowly healing, ulcers 
which persistedi for about 5 days. Tn one case blisters appeared on the 
hands and fingers, producing ulcers which required a much longer 
time for healing than those in the mouth. Sometimes a conjunctivitis 
is observed and blisters may appear on the nose, ears, and other parts 
of the body. There may also be violent vomiting, diarrhea, and erv- 
thrism of the skin especially in children, and often with fatal results. 

The literature of veterinary and* human medicine contains numer- 
ous accounts of the transmission of foot-and-mouth disease to man 
through the milk of affected cows. Siegel had 6 deaths in 400 cases. 
The incubation period in these cases was apparently 8 to 10 days. 
Shivering, giddiness, and nausea appeared in a majority of cases. Tn 
some patients the teeth became loose, the breath was offensive, and hem- 
orrhage occurred from the mouth and stomach. 

In addition to the changes in the milk noted above Jensen reports 
that in advanced cases the milk becomes thin with a slimy cream, con- 
tains leucocytes and gland cells in unusual numbers and sometimes 
red blood corpuscles. The albumin and globulin appear to increase 
in quantity while the amount of casein and milk sugar diminishes. 

The milk appears to be most infectious when freshly drawn and 
its virulence gradually diminishes. An outbreak was reported by 
Hart in Aberdeen in which the skim milk was not virulent. The 
virus may be present, however, in the skim milk, buttermilk, butter, 
or even cheese. Schneider and other German investigators have 
clearly demonstrated the infectiousness of these products from cows 
affected with foot-and-mouth disease. Frohner investigated a case 
in a man who ate sweet butter from the milk of such cows. The 
disease appeared within 48 hours and ran the usual course with 
numerous blisters in the mouth audi on the face and ears. Vincent 
observed a number of cases in children in which only the throat was 
affected, with symptoms similar to those of scarlet fever. 

The virus of foot-and-mouth disease is not very resistant. Milk is 
rendered non-infectious by subjection to a temperature of 70° C for 10 
minutes, or by being boiled. Pasteurizing at 80°-85°C. is efficient 
according to Danish experience. On account of the extensive physical 
and chemical changes which the milk undergoes during the progress 



259 

of foot-and-mouth disease it can not be considered, as fit for man even 
after boiling. In the outbreak of the disease in New England the 
sale of milk was stopped as soon as the disease appeared and little 
opportunity was given for transmission to man. 

In the city of Lawrence, Massachusetts, however, Brush traced 5 
cases in children directly to the use of infected milk. The disease 
had existedi for some time in the dairy which supplied the milk before 
the premises were visited by the veterinary authorities. The symp- 
toms observed in the children were fever, vomiting, diarrhea, swelling 
of the tongue and the eruption of blisters in the mouth. Such milk 
should not be fed to infants at all and before being fed to calves, pigs, 
or chickens it should be boiled. 

Anthrax. — The bacilli of anthrax have been demonstrated in milk 
by Feser, Monatskov, Chamberland, Roux, Nocard,, and others. F. 
Baum not only found anthrax bacilli in the milk of cows suffering 
from the disease, but showed that such milk was infectious for small 
laboratory animals. He concludes, therefore, that the use of this 
milk is attended with great danger. In studying the behavior of 
anthrax bacilli in milk Caro found that in freshly drawn milk they 
increased for the first 3 hours and then diminished in numbers. They 
lost their virulence within 18 hours at a temperature of 37°0. and 
within 24 hours at 15° or 16°0. This fact is attributed to the forma- 
tion of acid in the milk. When magnesium oxid was added and no 
free acid allowed to develop for 24 hours the bacilli multiplied rapidly 
and retained their virulence. According to Mi quel and Oambier the an- 
thrax bacillus develops rapidly in milk, changing it within a few 
hours into a solid, clotted mass, surmounted by a clear alkaline liquid. 
If, however, the milk is in a thin layer and freely exposed to the air 
coagulation is not produced by the anthrax bacillus. 

TTeusinger claimed that the milk of cows suffering from anthrax 
had been shown to be virulent for man by numerous observations in 
the United States and Russia. TTeusinger, however, considered milk 
sickness as a human form of anthrax. On this point he was evidently 
in error, since these two diseases are recognized as distinct by all 
American writers. Williams says that malignant pustule in man may 
arise from using the milk and butter of affected cows. Intestinal 
infection with anthrax is rare in man and appears as an inflamed 
condition of the intestines and mesenteric glands. Outbreaks of 
anthrax have occurred in Delaware and Wisconsin and the disease 
appears to be permanently established in the Gulf States, especially 
in Mississippi. No authentic proof has been presented from these 
outbreaks, however, of the transmission of anthrax by means of the 
milk. Nevertheless, it is reasonably certain that anthrax bacilli may 
penetrate the intestinal mucous membranes of children and infected 
milk must therefore be considered dangerous. The anthrax bacillus 
does not appear in the milk until the disease is far advanced. The 
milk may then become bloody and is otherwise altered so as to be 



260 

unfit for use. Moreover, the symptoms of anthrax arc so pronounced 
that there is no excuse for failure to recognize the diseased condition 
and to exclude the milk from sale and also from use even for domesti- 
cated animals except after sterilization by heat. If proper care is 
exercised it is safe to permit the use or sale of the milk from healthy 
animals in a herd in which a few cases of the disease have occurred. 
If, however, the conditions are insanitary such milk is dangerous ; 
for the feces and urine of diseased animals may infect the stables and 
in this way anthrax bacilli may gain entrance to the milk during 
the process of milking or later in handling. 

Cowfox. — The teats are the usual seat of cowpox lesions. The 
vesicles formed during the course of the disease may easily- become 
ruptured in milking and the virus may thus gain entrance to the milk. 
Whether or not the virus is ever secreted directly with the milk isi not 
known. The disease is readily transmitted to man, especially to the 
hands and face. There are but few authentic instances, however, of 
transmission by means of the milk. The infrequency of transmission 
may be due, as Jensen suggests, to compulsory vaccination and the 
consequent immunity of man except to local infection in abrasions 
of the skin on the hands and face. The virus is quite resistant and 
man is naturally susceptible. In Edinburg two outbreaks of sore 
throat occurred in a boys' college and involved 134 cases. The symp- 
toms were headache, lassitude, bleeding at the nose, fetid, breath, gas- 
tric disturbances, red and swollen patches on the mucous membrane 
of the mouth, etc. These epidemics were traced to the milk supply 
and were successfully checked by boiling the milk. One veterinarian 
diagnosed the disease in the cows as cowpox; another dissented from 
this opinion. In an outbreak described by Stern cowpox appeared 
in a dairy herd. Among the children who received this milk an epi- 
demic appeared in the form of skin eruptions which healed with the 
formation of scales. In cases of cowpox the milk may become thin, of 
bluish color, and readily coagulable. One attack of cowpox in man 
gives protection against further attacks of the disease and also against 
smallpox. 

Rabies. — The virus of rabies is found in the nervous system, sali- 
vary glands, saliva, bronchial mucus, and milk. Peuch, ISTocard, Per- 
roncito, Bardach, and others have shown that the virus may be ex- 
creted with the milk. In one case it was found that the milk of a 
rabid woman was infectious for rabbits and guinea pigs but not for 
her child. Rabies can not readily be transmitted by infection through 
the alimentary tract. Numerous experiments have been made in 
feeding the milk of rabid cows to laboratory animals. Negative re- 
sults have been obtained in all cases. The digestive juices may 
render the virus harmless. There is always the possibility, however, 
of infection through a decayed tooth or through abrasions of the 
mucous membrane of the mouth and pharynx. The milk of rabid 
animals should not be used for any purpose. 



261 

Tetanus. — No evidence has been presented to show the transmission 
of tetanus through the milk. Infection may take place, however, 
through the walls of the alimentary tract if lesions are present. The 
spores of tetanus may gain entrance into the milk from fecal matter 
in stables. The milk of cows affected with tetanus should not be 
used. Ordinarily such cows will not be milked. 

Pleuro-pneumonia. — It has not been definitely determined that 
man is susceptible to this disease in any form. The milk from af- 
fected cows quickly separates into cream and serum-like layers. The 
fat content diminishes and the albumin increases in amount. These 
changes furnish sufficient reason for prohibiting the use of the milk. 
No case of pleuro-pneumonia has been known in the United States 
since the disease was eradicated by the Bureau of Animal Industry. 
In Europe several cases have been reported in which children devel- 
oped symptoms of pneumonia and other pathological conditions after 
drinking milk from affected cows. In a few instances the lesions 
closely resembled those of pleuro-pneumonia in cattle. The fact re- 
mains, however, that the virus has never been found in the milk. If 
an outbreak of the disease should occur the necessary quarantine 
measures would be so strict, as to prevent the use of the milk. 

Actinomycosis. — This disease is of quite common occurrence in 
the udder of cows. It occurs still more frequently in the sow's udder. 
The human form of the disease appears to be identical with that ob- 
served in animals. It is generally believed that the ray fungus which 
causes this disease is found on cereals, grasses, and other food plants, 
and gains entrance to the animal organisms through skin wounds or 
through the alimentary tract. Accordingly the majority of cases in 
man are probably acquired in the same way as those in animals. The 
ray fungus has never been demonstrated in milk. Nevertheless when 
the disease occurs in the udder, especially in the primary form, the 
organ is greatly altered by the formation of tubercles throughout its 
substance. The actinomycotic processes may slowly extend to the 
outside of the udder and form running sores. It is apparent, therer 
fore, that the milk may become infected in the udder or in the process 
of milking, from the sores on the udder. Man may become infected 
through decayed teeth or lesions in the digestive tract. The milk of 
actinomycotic cows should therefore be excluded from the market. 

Milk sickness. — The nature and etiology of this disease have never 
been well understood. Fortunately the disease is yielding to better 
cultivation of the soil and drainage of marsh lands. Heifers, steers, 
and bulls show pronounced symptoms. Cows in full lactation, how- 
ever, show no symptoms of the disease although their milk may be 
exceedingly virulent. Calves, pigs, and man are affected by drinking 
the milk. Calves and pigs tremble, vomit, and, frequently die as a 
result of the disease. In man the symptoms are weakness, loss of appe- 
tite, nausea, thirst, coated tongue, cold dry skin, offensive breath, 



262 

slow respiration and weak pulse. According to Law the temperature 
is often subnormal and never higher than 100°F. Chills' and head- 
aches do not occur. The bowels are inactive. The patient is apathetic 
and finally passes into a comatose condition, dying without a struggle. 
In many cases a complete but slow recovery takes place. The mucous 
lining of the stomach and intestines is inflamed and sometimes 
sloughs off in patches. 

Infected cows which do not show any pathological symptoms while 
at rest may be made to do so by driving for a short distance. They 
will then tremble and the disease may be recognized. Infected timber 
land should be partly cleared so as to admit the sunlight freely. In- 
fected marsh land should be drained and planted to cultivated crops. 
This will check the disease among cows. The milk of cows which graze 
on infected pastures should never be used except after boiling or 
pasteurization. 

Mammitis. — The effect of the presence of mammitis upon the qual- 
ity of the milk depends upon the form and stage of the disease. Mam- 
mitis or garget of cows may be due to infection with streptococci, 
staphylococci, or bacilli of the coli-aerogenes group. The gland is 
affected with simple catarrhal, purulent, or gangrenous processes. Ab- 
scesses are frequently formed and ordinarily pus and disintegrated 
tissue escapes with the milk. Naturally, large numbers of bacteria 
are found in this purulent material together with fibrin and other ele- 
ments of the blood. Catarrhal mammitis affects the milk ducts. Their 
secretions thus become like bronchial mucus in cases of bronchitis. 
In parenchymatous mammitis the minute lactic canals, acini, and 
connective tissue are involved. The milk of affected quarters assumes 
a yellow color and has numerous clots in it. The milk from unaffected 
quarters soon shows the same changes and also becomes sticky. Later 
large quantities of pus are discharged with the milk, which becomes 
purulent and full of shreds of dead tissue. The milk from cases of 
mammitis is therefore utterly disgusting, quite aside from the con- 
sideration of any danger of infection which may be involved in drink- 
ing it. The presence of pus gives the milk a disagreeable flavor and 
makes it coagulate quickly. It is probable also that the pus is harm- 
ful to young children. Moreover, the streptococci and staphylococci 
which occur in milk from cases of mammitis have been shown to be 
virulent when taken in the alimentary tract. 

Niven, Hoist, Johannesen, and. others have reported several hundred 
cases in which human beings suffered from severe gastric and intes- 
tinal catarrh as a result of drinking milk from cows affected with 
garget. In all instances streptococci were found in the milk. The 
milk proved harmless when boiled. The milk of goats affected with 
gangrenous mammitis may also cause chills, headache, and vomiting. 
As shown by Moro such milk may be virulent even when used in 
small quantities in coffee. 



263 

Streptococcic sore throat. — This disease is often due to direct milk 
infection. Thus Edwards and Severn traced several cases of follicular 
tonsillitis to milk. The temperatures of the patients ranged from 
100° to 103 "F. and there was great prostration in a few cases. In 
the dairy herd which supplied the milk only one cow gave infected 
milk. In this cow's milk great numbers of staphylococci and strepto- 
cocci were found. The milk also contained considerable quantities of 
pus. The micro-organisms persisted in the milk of this cow for a 
long time and the same species were found in all the cases of sore 
throat. Numerous cases of this sort have been reported in medical 
literature. In the majority of such cases, however, no direct evidence 
was secured of a causal connection between mammitis in cows and 
sore throat in the human patients. The possibility of infection of the 
milk after it was drawn was usually not excluded. In all cases of 
mammitis the milk may contain pus and is therefore abnormal and 
highly objectionable. Moreover, in the infectious form of the disease 
the micro-organisms are virulent and harmful for man. From a 
clinical examination it is impossible to determine whether or not such 
virulent bacteria are present. It is necessary, therefore, to exclude 
from the market the milk from all cows affected with mammitis. This 
exclusion should apply to all of the milk from each affected cow. The 
disease tends to spread through the udder and an abscess in a diseased 
quarter may at any time break through into an apparently healthy 
quarter. The milk from these quarters may thus become infected in 
the udder. Furthermore, even if such extension of the pathological 
process has not taken place, the milk from the healthy quarters of the 
udder may readily become contaminated by carelessness in milking. 
Frequently the diseased quarters are milked first and then the healthy 
quarters, and without washing the hands. Often, too, the secretion 
of diseased quarters is milked upon the floor. Such practices can 
not be too strongly condemned. The streptococcus of bovine mam- 
mitis develops rapidly at temperatures of 16°-30°C. and occurs in 
enormous numbers in the milk of affected cows. 

Milk fever. — Although the essential nature of this disease has not 
been established it seems desirable to refer briefly to some recent 
observations regarding the toxicity of the milk of affected cows. Ac- 
cording to Delmer the milk rapidly separates into 2 layers, the upper 
of which is thick and yellowish and. occupies about one-fourth of the 
height of the column. The lower portion is of a bluish-white color and 
contains numerous colostrum corpuscles. Such milk was found to 
cause the death of healthy cows when inoculated intravenously. It 
proved virulent also for rabbits. From these experiments it appenrs 
that the toxic cause of milk fever may be found in the milk. At any 
rate there is no excuse for using such milk. 

Hemorrhagic enteritis. — This disease occurs much more frequently 
in calves than in adult cows. Jensen has shown that this affection is 
usually due to bacteria which belong to the hog cholera group. It is 



264 

not known whether the micro-organisms of this disease are directly 
transmitted with the milk. On account of the profuse diarrhea, 
however, the posterior parts of the cow and the floors become thor- 
oughly contaminatedi and the bacteria may thus easily gain entrance 
to the milk. Follenius and Gaffky have reported cases in which the 
milk from such cases was shown to be virulent for man, producing 
headache, fever, weakness, and diarrhea. 

Septic diseases. — In so far as the meat is concerned septicemia is 
the most dangerous to human health of all animal diseases. A large 
percentage of the most violent cases of meat poisoning are caused by 
eating the meat, of animals suffering from septic processes. No 
authentic instances are on record of the transmission of septic affec- 
tions by means of milk. It is highly probable, however, that such 
transmission does occur. 

As an example of this class of diseases we may mention septic 
metritis or inflammation of the uterus. In such cases the uterine 
exudate containing streptococci, staphylococci, coli bacillus, and pro- 
teus soils the posterior parts of the cow and may easily gain entrance 
into the milk. Milk containing these bacteria would be virulent for 
man, as well as for calves and pigs. 

It is likewise almost impossible to prevent contamination of the 
milk in cases of retention of the afterbirth. Septic bacteria are not 
always present in these cases. The milk should not be used until ihe 
nterus has resumed its normal condition and until the cow has been 
properly cleaned. 

Suppurating wounds, and phlegmonous, or erysipelatous processes in 
the skin, especially on or near the udder, give occasion to the almost 
certain contamination of the milk. The bacteria which thus fall into 
the milk along with other filth may cause enteritis in man. 

Moreover, the epizootic prevalence of septic calf lameness, calf 
dysentery, white scours, or calf diphtheria furnishes favorable condi- 
tions for the contamination of the milk. In herds in which such 
diseases prevail the milk is not fit for infants unless affected animals 
are isolated and all necessary sanitary precautions observed. 

There are a number of other malignant diseases of cows, such as 
hemorrhagic septicemia, rinderpest, malignant edema, malignant ca- 
tarrhal fever, broncho-pneumonia, etc., in which the possibility of 
infection of the milk can not be excluded. In all diseases accompanied 
with fever more or less serious metabolic disturbances occur and 
toxic substances may be found in the milk. The progressive dairyman 
in order to build up and preserve a good reputation for his milk and 
protect the health of his patrons will exclude the milk of all cows 
which are suffering from any acute disease. Milch goats affected 
with Malta fever may transmit the disease to man in the milk. 

In a study of the excretion of micro-organisms through the active 
mammary gland it should be remembered, that in general those bac- 
teria which have the power of producing hemorrhage or similar 



265 

changes in the mammary gland during which the normal structure of 
the organ is disturbed are most likely to be excreted in the milk. 
Mixed infection favors the excretion of bacteria from the udder. Thus, 
in cases of pure septicemia or anthrax the pathogenic micro-organisms 
are less frequently found in the milk than when associated with 
Bacillus bovis morbificans or some other organism with similar 
properties. 

Pathogenic bacteria may be present in considerable numbers with- 
out causing any changes in the milk. On the other hand Bacillus coli 
may rapidly and completely sour and coagulate the milk, Proteus 
vulgaris may decompose it, and Bacillus enteritidis sporo genes may 
cause a decomposition and formation of gas. In this connection it is 
important to know how long disease germs may retain their virulence 
in milk. According to Dawson the bacillus of swine plague becomes 
attenuated in milk within 36 hours and loses its virulence entirely 
within 72 hours. This effect is apparently due to the acid formed in 
the milk. Dawson found that in butter the tubercle bacillus retains 
its virulence quite uniformly for 3 months, after which it becomes 
gradually attenuated but is still virulent at the end of a period of 8 
months. As a rule bacteria thrive best in a neutral medium. They 
are therefore somewhat unfavorably affected by the souring of milk. 
Milk, however, is usually consumed in a fresh condition. 

The foregoing discussion has been concerned with diseases which 
may be transmitted from cows to man through the agency of milk. 
We have now to consider the transmission of human diseases in milk 
as the result of infection or contamination of the milk after it has 
been drawn. The list of known milk-borne diseases is not very large. 
The most important are typhoid, scarlatina, diphtheria, and cholera. 

There are certain general characteristics of milk-borne epidemics 
which greatly assist in the identification of the source of infection in 
milk. In the first place the distribution of such epidemics conforms 
with the route of a certain milkman. The disease prevails most 
extensively among the middle and upper classes who drink more milk 
than the poor. The upper classes live in more sanitary surroundings 
than the poor and are therefore less exposed to the usual sources of 
infection than the latter. Milk is at once to be suspected if typhoid 
or scarlet fever becomes epidemic among the upper classes of a certain 
section of a city. Milk-borne epidemics naturally prevail more ex- 
tensively among the individuals who drink most milk. The apparent 
exemption from infection of certain members of a family is thus 
easily explained. As a rule women and children drink more milk 
than men and are therefore more affected in milk-borne epidemics 
than men. Newman has called attention to the fact that the period 
of incubation is much shorter in cases of typhoid fever, scarlet fever, 
and diphtheria when these diseases are carried in milk than when they 
arise from some other source of infection. Thus when conveyed in 
milk the first symptoms of typhoid, fever may appear within a few 
days (sometimes 2 days) and those of scarlet fever and diphtheria 



266 

within a few hours. This is probably due to the fact that the virus 
of these diseases multiplies rapidly in milk and the victim receives 
much larger quantities of it than he would by any other method of 
infection. 

Again in milk-borne epidemics the outbreaks occur suddenly. A 
large number of persons are affected at once or in rapid succession, 
much more rapid than could occur by infection from person to person. 
The outbreaks stop as suddenly as they begin. This follows as a 
result of excluding the infected milk from the market, boiling the 
milk, or from the extinction of the original source of infection. 
Finally, the symptoms in cases of infection from milk are less severe 
and the rate of mortality is lower than normal. Most cases are mild. 
Scarlet fever, when conveyed by milk, shows characteristic modifica- 
tions in a large percentage of cases. Along with typical mild cases 
of scarlet fever there appear many cases in which the symptoms are 
confined to the throat. The true nature of such cases is often misun- 
derstood and, they are wrongly diagnosed as simple cases of sore 
throat. The symptoms of typhoid fever and diphtheria conveyed by 
milk do not differ except in mildness from typical cases. Milk-borne 
diphtheria is perhaps less contagious than cases due to other sources 
of infection. 

It is obvious that milk may easily become infected with the virus 
of human diseases. The pathogenic organisms of these diseases are 
often present on the clothing of attendants or in their expectorations, 
feces, or urine d.uring convalescence' and even for long periods after 
recovery. If such attendants are careless in their habits it would be 
almost miraculous should the milk fail to become contaminated. 
Abundant opportunity for contamination is offered during • milking, 
handling of the milk on the farm, transportation to market, bottling, 
distribution to individual patrons, and during subsequent care in the 
household. In connection with the study of an outbreak of typhoid 
fever in 1857 Taylor first demonstrated that milk may act as the 
vehicle of infectious human diseases. Since attention has been di- 
rected to this source of infection hundreds of outbreaks involving 
thousands of cases have been definitely traced to a contaminated milk 
supply. It is highly probable, however, that milk is suspected in only 
a small percentage of the cases in which it is the carrier of infection. 
In this regard the danger of an unregulated milk supply can not be 
overestimated. 

Typhoid fever. — Extensive and classified lists of outbreaks of 
typhoid fever carried by milk have been collected by Hart, Freeman, 
Newman, Schuder, Kober, and others. Among 195 epidemics tabu- 
lated by Kober the disease prevailed at the farm or dairy in 148. In 
67 outbreaks the milk became infected, through. the water with which 
the utensils were washed and in 16 instances infected water was used 
in adulterating the milk. In other instances the cows drank and 
waded in infected water, the dairy employes served also as nurses of 



267 

typhoid patients, or the patients continued at work while suffering 
from a mild form of typhoid,. The seriousness of these epidemics is 
apparent from statistics collected by Hart, according to whom it ap- 
pears that in 51 outbreaks of milk-borne typhoid there were 3,500 
cases and 350 deaths. 

It is easy to see how milk may become infected with the typhoid 
bacillus. It may be well, however, to discuss briefly some of the 
methods of such contamination. If milk utensils are washed with 
polluted water infection may readily be carried to the milk. In most 
"instances infected water comes from wells and small streams. Both 
these sources of water supply are much exposed to pollution. Milk 
may be still more certainly and more extensively polluted by adding 
water to it for purposes of dilution or adulteration. Again milk may 
become contaminated by direct or indirect contact with typhoid pa- 
tients. If the same person who nurses a typhoid patient also milks 
the cows, the hands may easily become infected and, the typhoid bacilli 
may thus gain entrance to the milk. Many such cases have occurred 
and this fact serves to illustrate the danger to the public health from 
the non-regulation of the workmen and premises of dairy farms. At 
least two outbreaks of typhoid have been traced to infection of the 
milk by means of air carrying typhoid bacilli from dried excrement. 
This shows the importance of burning or otherwise disinfecting all 
excrementitious matter, including urine, from typhoid patients and also 
of protecting milk against contamination with dust. In another out- 
break the milk utensils were wiped with a dish cloth which was also 
used among typhoid patients. Sealed milk cans sometimes leak when 
sunk in water for cooling purposes. One instance is known where 
the milk became infected in this way. When it is remembered that 
the feces and urine of typhoid patients may contain the bacilli during 
convalescence and for months after recovery it will be apparent how 
frequently opportunity for infection is offered and how varied the 
methods are by which such infection may take place. In recent years 
evidence has been accumulating regarding the agency of flies in the 
distribution of typhoid fever. Flies frequent feces. Fly maggots 
live in such material and adults feed upon it. They are also greatly 
attracted by all kinds of human food, perhaps particularly milk. 
Flies have been shown to carry typhoid bacilli on their legs and other 
parts of the body. It is obvious, therefore, that flies may carry the 
bacilli from human feces to milk and infect the latter. Other insects 
with similar habits may also be instrumental in spreading infection. 

The typhoid bacillus thrives well and grows rapidly in raw or steri- 
lized milk. It retains its virulence for long periods in milk and its 
products (according to Plant, for 30 days in milk, 48 hours in butter- 
milk, 21 days in butter, and several days in cheese). Bolley inocu- 
lated milk products with typhoid bacilli for the purpose of determin- 
ing how long they retain their virulence. Bacilli placed in small pits 
in salted butter remained virulent for 7 to 10 days. They remained 



268 



alive lor several months in cream, hill Icrini Ik, and uusalled butler. 

In sweet milk the germs developed in great numbers and bhe milk 
became acid but did nol coagulate. In mixed infection <>l milk the 

typhoid bacilli were not OUtgrOWn bv Other Species l>nl in sonic cmscs 

became predominant. 

The bacillus does not sour the milk or alter its appearance in any 
way. [t does not ooagulate milk like the closely related coli bacillus 
which occurs more frequently in milk. Moreover, the typhoid bacillus 
dors not form gases, lis multiplication is somewhat checked by the 
souring of milk but is not entirely stopped, and its virulence is nol 
thereby destroyed. According to Sternberg its virulence is destroyed 
by subjection to a temperature of 56°0. for 5 to H* minutes. In 
milk the typhoid bacillus is destroyed by the ordinary process 
o\' pasteurization at 80°C or even al 70°C. for ;i period of l" 
minutes. Pasteurized milk is therefore ;i safe article of food in so far 
us typhoid fever is concerned, [t must be remembered, however, that 
the milk may l>e become reinfected at any time through the agency o\' 
flies. 

The commonest way in whioh milk becomes infected with the i\- 
phoid bacillus is through polluted water, and in adulterating the milk 
or in washing milk receptacles. Dairyman who desire to furnish sani- 
tary milk to their patrons may easily avoid danger oi' typhoid infec- 
tion by using for washing purposes water which has been boiled or by 
soalding all milk receptacles and exposing; them to bright sunlight. 
Ff nil typhoid feces and urine- are destroyed, the danger of transmis 
sion through the agency of llies will be removed. The sanitary dis- 
posal of typhoid exorementitious matter will also protect the water 
supply of the farm. 

Sca/rlei fever. Although the pathogenic mioro-organism of scarlet 
fever is not known, it, has been shown beyond reasonable question thai 

the disease may he conveyed by milk. The most probable bacterial 
Cause of Scarlet lever is StreptoCOCCUS SCdrloMnde, In 99 epidemics of 

milk-borne scarlet lever tabulated b\ Kober the disease prevailed at 
the dairy or milk farm in 68 instances. In 6 outbreaks persons in 

some way connected with the dairy had been exposed to the disease. 

Moreover, in IT instances the milk became infected from contact with 
attendants who were convalescing from the disease. Finally in li> out- 
breaks infection was attributed to disease of the cows (puerperal fever, 

ulcers on the teals, etc.). In nearly all epidemics o( milk-borne scar- 
let fever evidence has been produced thai individuals actually suffer 
Lng with the disease or carrying the contagion on their clothes have 
taken pari in milking or distributing the milk to patrons. On account 
of the highly infectious character of scarlet lever it is nol difficull t<> 

understand how the milk may thus become contaminated. Nearly all 
these epidemics are reported from England and America. In conti- 
nental Europe On the ether hand physicians seem generally to doubt, 
the importance Of milk in the transmission {)( scarlet fever. This is 



269 



doubtless due in part to the fact that milk in more extensively pas 
teurized before using in continental Europe. 

Attention has already been called to the fad that mill* borne scarlel 
fever is often mistaken for cases of ordinary sore throal on account 03 

the fact bhat the symptoms may be almost entirely fined bo the 

throat. As noted by Parsons, Buchanan, and others the cash may be of 
short duration and desquamation very slight, Moreover, nephritis as :i 
complication is much rarer than after ordinary cases of scarlel fever. 
The vomiting and diarrhea frequently observed in the mill? borne dis 
ease are perhaps due bo mills poisoning, since the infection ol milk 
with scarlet fever furnishes good evidence of carelessness and insani- 
tary handling of milk. The fact thai this form of scarlel fever is 
imi only slightly infectious may well be attributed to the small extent 
of skin eruption and desquamation, as suggested, by N"ewmah, li 
has also been observed that after drinking infected milk persons who 
have already had scarlet fever exhibit merely mild throat symptoms 
while others may suffer more severely. The virus of scarlet fever may 
lie destroyed by sterilizing the milk or by ordinary pasteurization. 

Power studied an outbreak of scarlet fever in London and came to 
the conclusion that if was transmitted, by cows suffering with erup 
lions on llie adder and teats. Klein obtained Micrococcus scwldtinine 
from the diseased tissue of these cows and succeeded in reproducing the 

disease in cnlves hv inocnhil ion. Tims far, however, no nnexceplioii 

able evidence has been produced that cows may become infected with 
scarlet fever or that the disease may he transmitted, to man from < 1 i s ■ 
eased cows, Supposed e;ises of l his sort may well be attributed to 

infection from some oilier source or imiv he referred lo :is pseudo- 
SCarlet fever. 

Diphihv.ria. In a lisi of -'!(*> milk home epidemics of diphtheria 
us tabulated by Kober the disease existed ;H the dairy farm in L8 
instances while in L2 outbreaks the disease was attributed to direct 
transmission from cows suffering with mammitis or ulcers on the 
beats. The diphtheria bacillus thrives well in milk, [t grows ;ii all 
temperatures between 20° and 87°C. If grows more vigorously in 
raw than in sterilized milk. The bacillus has not heen isolated from 
market milk except in a few instances. 

The diphtheria bacillus is widely distributed and may poswibly live 
for some l iniei as :i saprophyte in I he soil. Moreover, if has been dem- 
onstrated that if may persisl in the throat of convalescing diphtheria 
patients for a period of 8 weeks or perhaps Longer. These facts serve 
to indicate how frequently milk may be exposed to infection us a 
result of carelessness in the personnel of dairy farms. Outbreaks of 
diphtheria due to drinking infected milk have occurred in England, 
Scotland, Onited States, Denmark, Sweden, Germany, and elsewhere. 
The diphtheria bacilli are not affected by the souring of milk and 
therefore probably occur in butter and other milk products. They are 
destroyed in milk by subjection i<> a temperature of 70°G for a period 



270 

of 10 minutes. The number of cases of diphtheria transmitted by 
milk, is small as compared with those which arise from other sources 
of infection. Tt is evident, however, that many cases of transmission 
in milk escape notice and sufficient instances have been definitely as- 
certained to lend the matter considerable importance from the stand- 
point of human health. 

Many cases have occurred particularly in England of apparent 
transmission of diphtheria, directly from cows to man. In one out- 
break of this sort Klein asserted positively that the diphtheria bacillus 
could be demonstrated in the milk of a diseased cow even when drawn 
under all antiseptic precautions. Klein states that the bacilli were 
present at the rate of 32 per cubic centimeter of milk. 

In 1904 Chalmers reported an outbreak of septic sore throat and 
diphtheria among the staff of the Belvidere Hospital, Glasgow. In 
all, 39 cases with diphtheritic symptoms were observed. In a majority 
of cases it was impossible to understand how infection could have taken 
place from one person to another. In the dairy herd which supplied 
the milk an infectious teat eruption occurred and spread rapidly. 
The disease also affected the hands of the milkers. Chalmers be- 
lieves that "there can be little hesitation in regarding the majority of 
the throat affections which came under observation at the hospital as 
directly resulting from the teat eruption." At any rate the outbreak 
stopped as soon as the milk was boiled. 

Robertson traced a serious outbreak, diagnosed as diphtheria, to 
ulcers on cows' teats. The epidemic ceased as soon as the milk of the 
affected cows was excluded from sale. It was not possible to isolate 
the diphtheria bacillus from the ulcers on the cows' teats. It was 
suggested that the disease was cowpox. 

Cows have been inoculated with the human diphtheria bacillus but 
no disease comparable with diphtheria has been produced in this 
manner. The relationship between human and bovine diphtheria is 
under dispute. Most investigators, however, are inclined to believe 
that the two diseases are distinct and unrelated. Septic sore throat 
may result from drinking the milk of cows with ulcerated teats, but 
the disease is probably not true diphtheria. According to the evidence 
now available it appears that diphtheria bacilli in milk must be con- 
sidered as coming from cases of human diphtheria and as gaining 
entrance to the milk after it has been drawn. 

Cholera. — The cholera vibrio thrives better in sterilized than in 
raw milk. It can not live in an acid medium and soon dies in sour 
milk and buttermilk. The number of authentic examples of trans- 
mission of cholera in milk is limited. Simpson reported the most 
striking outbreak of this sort, On board a vessel in the harbor of 
Calcutta 10 men drank some native milk which had been diluted with 
infected water. Of this number 4 died, 5 recovered after serious ill- 
ness, and one, who drank only a small quantity of the milk, was only 
slightly affected. The cholera vibrio may be destroyed by boiling the 



271 

milk. It should be remembered, however, that boiling destroys all the 
common milk bacteria, and prevents the souring of the milk, thus 
furnishing • the most favorable medium for the growth of cholera 
germs which may gain entrance to the milk after it has been sterilized. 
During cholera epidemics the milk should be boiled immediately before 
using. 

Thrush,. — Oidium albicans, the fungus which causes thrush, fre- 
quently occurs in milk. It thrives well in milk, and in this medium 
gains entrance to the infant's throat where the disease becomes estab- 
lished. Milk is undoubtedly an important carrier of this disease. 

Diarrhea. — According to statistics collected by Newsholme only 9 
per cent of the fatal cases of diarrhea in children occur in those which 
are fed at the breast. Numerous cases of diarrhea in adults accom- 
panied with chills, fever, and general weakness have been traced to 
cows affected with enteritis, or to infection of the milk with bovine or 
human fecal matter. Such infection usually takes place by means of 
polluted water or dust. As noted above, diarrhea often appears in 
connection with sore throat as a result of drinking milk from cows 
suffering with mammitis. A considerable percentage of these cases 
of diarrhea are due to the excessive numbers of the coli bacillus com- 
monly found in unclean milk. The prevalence of coli bacillus indi- 
cates fecal pollution and suggests the obvious remedy of grooming the 
cows and protecting the water supply. 

Tuberculosis. — The transmission of this disease from cows to man 
has already been discussed. Tubercle bacilli may also gain entrance 
to milk directly from consumptives, particularly if they have careless 
habits. Tuberculous patients should not be employed in handling 
market milk, since they may spread contagion about the stables and 
may infect the milk directly by coughing. 

Other diseases. — Milk has been shown to be a favorable culture 
medium for the pathogenic organisms or virus of various other dis- 
eases such as erysipelas, pneumonia, etc. The possibility can not be 
excluded that milk may serve to carry smallpox, measles, bubonic 
plague, syphilis, dysentery, cerebro-spinal meningitis, etc. Authentic 
cases of such transmission perhaps do not exist, but it is for obvious 
reasons a very difficult matter to demonstrate the causal connection 
of milk with outbreaks of these diseases. 

It is not necessary or desirable to adopt an alarmist position with 
regard to the general question of the transmission of infectious dis- 
eases through the agency of milk. Indifference in this regard, how- 
ever, constitutes a great source of danger to the public health. This 
danger has not been overrated in the above discussion. It must be 
admitted as highly probable that milk serves to transmit far more 
cases of infectious diseases than are definitely traced to the milk 
supply. 



272 

The prevention of the transmission of infections diseases by milk 
may be largely effected by the following measures : 

(1) Cleanliness of the cows, stables, fodder, attendants, all milk 
utensils, milk rooms, etc. 

(2) The sterilization or pasteurization of milk, if it can not be 
consumed in a fresh condition or can not be refrigerated. 

Moreover, in order to secure the best sanitary conditions for milk, 
it is necessary to carry on an increasing crusade for greater domestic 
and civic cleanliness with regard to the storage and handling of milk 
and the prevention of the dust nuisance and the fly nuisance. 



273 



CHAPTER XIV. 

DIETETICS OF MILK WITH REFERENCE TO INFANT 

FEEDING. 

BY 

Louise Tayler-Jones, M.S., M.D., 
Washington, D. C. 

The whole movement toward milk purification has received its 
impetus largely through the infant. This is true for several reasons. 
Although milk may be looked upon as a universal food, it is the young 
of all species w T ho use it as their whole food. Adults among the poor 
practically never use it. Adults among the well-to-do use it most 
extensively in cooking, where it is harmless, but even when they use 
it raw they are not affected by the products of the dirt bacteria ordi- 
narily found in such great numbers. So that for a long time it was 
thought that if no adulterations were used and the proper standards 
of total solids and fats were observed, the milk supply was as satis- 
factory as could be expected. With the advance in bacteriological 
methods and the more frequent recording of vital statistics, people 
awakened to the fact that babies were ill and dying in great numbers 
and that most of these babies were on food other than mother's milk, 
usually cow's milk. But it was a long time before public opinion was 
well aroused and even today most people are ignorant of the true 
conditions on the average dairy farm. Let us consider milk then from 
the standpoint of dietetics" for infants. 

Diet is the most important branch of pediatrics. Slight ailments 
of babies, as well as more serious diseases, find their source in food 
oftener than in any other one etiological factor. The younger the 
child the greater is the stress to be laid on the proper feeding as a 
relief from diseased conditions, for the younger the child the nearer 
is it to the perfect development with which the average child is en- 
dowed at birth and the less chance there is for the many diseases 
which come to it later from without. 

Mortality. 

At this early stage then, one deals with the biologic animal rather 
than, as so frequently happens later, with the pathological animal. 
In the face of this statement one approaches the mortality records 
with a feeling of unbelief, with wonderment and with shock. One- 
fourth of all deaths in the large cities of the world are of persons under 
one year of age ! The knowledge that the baby, whose expectation of 
life should be the best, has a poorer chance at birth than a person 
seventy years of age is a just cause for alarm. 



274 

In the District of Columbia the infant death rate, though high, has 
been improving each year. In 1906 there were 6,529 births and, for 
the same period, 1,233 deaths in infants under one year of age. This 
means 188.8 deaths during the first year of life for every 1,000 births. 
(For 1900 there were 281 per 1,000 births.) Of these deaths 429, 
or one-third, were directly due to causes, like malformations and con- 
tagious diseases, other than intestinal disturbances. Regarding deaths 
from diarrhoeal diseases the accompanying table (Table I) will show 
the conditions in Washington for the last twenty-five years : 

Table I. 

Death rate from Diarrhoeal Diseases for Children Under 
2 Years of Age per 100,000 People per Annum. 

1880-1884 162 

1885-1889 168 

1890-1894 175 

1895-1899 135 

1900-1904 109 

1905 104 

1906 97 

From 1880 to 1895 the death rate from diarrhoeal diseases per 
100,000 people per annum for children under two years of age was 
about 170. In 1895 it was 135, and has decreased each year until 
in 1906 it was 97. The only explanation of this sudden lessened 
mortality from intestinal disturbances in infants in 1895, after 
fifteen years of even high mortality, is a law passed, March 2, 1895, 
"regulating the sale of milk in the District of Columbia and the es- 
tablishment of dairy and dairy farm inspection under the provisions 
of that law." (Woodward). 

In 1900, when Washington had an infant mortality of 281 deaths 
during the first year per 1,000 births, Charleston, S. C., had the high- 
est rate of 419.5 per 1,000 births. At the same time the 'States, as 
would be expected, showed a lower death rate. Of the few States 
where vital statistics are recorded, Rhode Islands stood highest with 
197.9, and Michigan lowest with 121.1 per 1,000 births. But nearly 
ten years have elapsed and all these towns and States have doubtless 
made as big strides as Washington in lessening the infant death rate. 

In foreign countries the conditions seem as bad as with us, and in 
some places, worse. In Berlin the record for five years (1900-1904) 
averaged 207.8 deaths under one year per 1,000 births. Prausnitz 
(Pfaunder and Schlossman) represented in a graphic manner all 
deaths in Germany during one decade (1871-1880) per 1,000 people. 
His chart shows a very rapid decrease in the mortality from birth to 
two years of age, followed by a more gradual decrease to fifteen years 
of age. From the fifteenth year the chances for death increase slowly 
but continuously. The Germans have a wealth of statistics in regard 



275 

not only to the causes but to the circumstances of death. Their death 
returns of infants show whether the child was breast fed or artificially 
fed,. In Berlin (Harrington) the average for deaths of breast-fed 
babies to all deaths of babies in 1900-1904 was 9.7 per cent (less than 
one tenth.). Of 65,720 deaths reported by Boeckh* (Abbott) the 
number seems to be even smaller, as shown in the accompanying table 

Table II. 

Food Deaths Births 

Mother's milk 7.4 per 1,000 

Mother's and cow's milk 21.4 " 

Cow's milk only 42.1 " 

Milk substitutes 67.7 " 

Cow's milk and milk substitutes. 125.7 " 

In France conditions have been similar (Planchon). Of 2,840 
deaths during the first year of life. 1,362, or 47.9 per cent were due 
to intestinal disorders. Of these of intestinal origin only 9.9 per cent 
(136) were breast-fed. This sihows a remarkable prevalence of 
diarrhea among the bottle-fed babies. In the agitation in France to 
save citizens, factories post placards stating the advantage of breast 
feeding and provide special rooms for this purpose. In some parts of 
Italy there is a law requiring such a room in factories where more 
than fifty women are employed. 

It would seem then, from the excessive mortality among infants, 
that steps should be taken to decrease this death rate as far as possible. 
Much has been done, as will be shown later, but there is yet the most 
to do. ~Nov has there been a great deal of difficulty, in late years, in 
placing the blame. It is not that the cause of the high mortality elim- 
inates only the weak, for it is well known that those communities with 
the highest infant mortality have also the highest mortality for 
children from one to five years of age. It is not among breast-fed 
babies, for the mortality among them is shown to be very small in 
several countries, and what will hold in those parts in this particular, 
will hold approximately in our own cities. It is not to be accounted 
for entirely by hot weather and crowding and inherent defects. All 
the difficulties that have been experienced have not been due to the 
inability of the physician to modify the milk satisfactorily, however 
difficult that may have been at times. But it is due, in otherwise 
simple feeding cases, to intestinal troubles developing often in healthy 
babies fed on dirty milk. The best substitute food practically is cow's 
milk, and for such a purpose it must be used. The only conclusion is 
that cow's milk must be either pure or purified. It is for the purpose 
of studying this side of the question, more than any other, that milk 
commissions have been formed and have labored, that milk committees 
have become important in the medical societies, and that a general 

* International Statistical Bulletin, Yon II, No. 2, p. 14. 



276 

crusade has been started against dirty milk. It is partly, too, for that 
purpose that this report has been written, and, the subject certainly 
can not be avoided later in this chapter. 

Physiology of Mother's Milk. 

The question of feeding- a baby has ever been made prominent. 
The helplessness of the infant and the necessity of caring for it have 
been enhanced by the difficulties attending the proper digestion and. 
assimilation of its food,. A study of the principles underlying this 
proper assimilation may be considered profitably at this point. The 
natural food of any new-born mammal is its mother's milk. These 
different mothers have in their milks the same elements, namely, fat, 
sugar, proteid, mineral salts, and water. They appear in" different 
proportions in different animals, as may be seen from the accompany- 
ing table 

Table III. 

Fat Sugar Proteid Mineral Water 

Salts 

Cow 4.00 4.50 3.60 .65 87.25 

Goat 4.10 4.45 3.70 .85 86.90 

Woman 4.00 7.00 1.50 .20 87.30 

Mare 1.10 6.65 1.90 .30 90.05 

Ass 1,30 6.30 2.10 .30 90.00 

They also vary greatly in the same animal, and this table represents 
only a good average for each. These elements, which are supplied 
for the individual baby after birth, must be properly digested before 
their products can be taken into the blood for building up the different 
tissues. Certain substances are found in the digestive tract to do this 
work. Besides the organized ferments like yeast and bacteria, there 
are present in the digestive tract certain unorganized ferments called 
enzymes. Each enzyme has a distinct, a specific work, to do. There 
are 

a proteolytic enzyme (example, pepsin) for splitting proteids, 

an amylolytic enzyme (example, ptyalin) for splitting starch. 

a lipolytic enzyme (example, lipase) for splitting fats, 

a sugar splitting enzyme, 

a coagulating enzyme (example, rennin) for coagulating or clot- 
ting, and an oxidizing enzyme. 

Each of these is found in the infant and is ready to function at 
birth, except possibly the amylolytic enzyme. As a result, when the 
slightly alkaline mother's milk enters the infant's stomach no change 
takes place immediately because the rennin, which soon coagulates 
the casein into a fine flocculent curd, can not act until hydrochloric 
acid is secreted. The act of eating stimulates the secretion of the 
acid. Sufficient is secreted by the end of two hours to have completed 
the coagulation and some is left, so that there is free hydrochloric acid 



277 

in the stomach. The coaguTum is then digested in part by the pepsin. 
There is no action in the stomach on fats, sugars.; or starches. As 
the enzymes which act on them are in the intestine, (except ptyalin 
in the saliva) the greater part of digestion is carried on in the diu> 
denum. If the stomach is too alkaline the food will be carried into 
the intestines before peptic digestion can take place. If there is too 
much fat present it surrounds the particles of the coagulum and the 
proteolytic enzyme can not reach the casein. So it is seen that each 
element must be taken in the food in sufficient quantities to develop 
the proper use of these enzymes but must not interfere with the 
proper chemical and mechanical workings of digestion generally or 
there will follow conditions varying from acute intestinal disorders 
to very slowly progressing general diseases. 

The amount of food an adult should take must be sufficient to repair 
the waste to the tissues and sustain the normal temperature. But in 
babies the metabolic equilibrium must be more than sustained, since 
there is continuous necessity for increased size and the repair there- 
fore must exceed the waste. Each element of food has the power 
to do this to a different degree, depending on the amount, of energy 
it can produce. A standard has been adopted and called a calorie. 
This (large calorie) is the quantity of heat necessary to raise 1 kilo- 
gram of water 1°C. in temperature. The amount of energy or num- 
ber of calories of each element has been calculated by burning it in a 
calorimeter and the result has shown that 
1 gm. of fat yields 9.3 calories 

1 gm. of sugar yields 4.1 calories 
1 gm. of proteid yields 4.1 calories 

Then a litre of mother's milk, if it contains 4% fat, 7% sugar, and 
1.50% proteid will yield 372 calories in fat, 287 calories in sugar, 
and 61.5 calories in proteid, or a total of 720.5 calories. 

These physiological conditions are the bases for many of the various 
views held by podiatrists the world over. 

Mothers Milk. 

No food, is so good for a baby as that which nature intended for it, — ■ 
the mother's milk. The importance of this can not be too much 
emphasized. It is better digested and better absorbed than any other 
food devised. Nearly every mother should be able to nurse her child. 
Mme. Dluski holds that 99% of mothers can nurse their children. 
Cases are seen frequently where, with only a small amount of milk 
secreted, there might be some temptation to take the baby off the 
breast, whereas later the supply increased quite sufficiently. In the 
school of midwifery in Stuttgart in 1882 ITerdegen found 23% of 
women were able to nurse their children ; in the same institution in 
1904 Martin found nearly 100% were able to nurse (Camerer in 
Pfaundler and Schlossman). This suggests some discrepancy in the 
statistics, but it certainly seems that more insistence on the part of 



278 

the physician can do much to lessen the number of babies taken from 
the breast. There is no doubt that babies are taken from the breast 
with insufficient reason. Much can be done toward modifying the 
breast milk from a poor food or rich unhealthful food to a normal 
state. If an examination is made to find the fat percentage and pro- 
teid percentage, adjusting the diet and exercise to suit the conditions 
found will frequently give most satisfactory results. 

The best practical fat test for woman's milk, where the quantity is 
so limited, is the Leffman and Beam modification of the Babcock test.* 
The requirements for the fat test are (1) a centrifugal apparatus, (2) 
two small bottles like the Babcock test bottles (but with about one- 
sixth the capacity) with 100 markings on the neck, (3) two pipettes 
marked at 2.92 cc. exactly, (4) a small .pipette graduated in one-tenth 
c.c, (5) C. P. sulphuric acid, sp. gr. 1.84, (6) concentrated hydro- 
chloric acid, and (7) fusel oil. With one pipette put 2.92 c.c. of 
mother's milk into the bottle, tipping the bottle and allowing the milk 
to flow carefully down one side of the neck. With the other pipette, 
and even more carefully and slowly, allow 2.92 c.c. of pure sulphuric 
acid to flow in on top of the milk. Mix slowly and thoroughly. With 
the small graduated pipette add 0.6 c.c. of equal parts hydrochloric 
acid and fusel oil. If this does not reach to 5 (the top mark of the 
scale on the neck of the bottle) add sulphuric acid and_ water, equal 
parts, sufficient to bring the surface to 5. Stopper the bottle and 
invert gently several (2-4) times. It is advisable to use the first 
breast milk in one bottle and the last milk (after nursing) in the 
other. The average can be obtained from the two, and two bottles have 
to be used to preserve the balance of the centrifuge. Revolve speci- 
mens in centrifuge for five minutes, 100 revolutions of the handle per 
minute. Upon removing the bottles the fat will be observed in the 
neck and sharply defined. Read from the lowest edge of the fat to 
the top of tbe meniscus at the surface. As each division represents 
3-10 of 1% of fat, multiply the number of divisions by .003. For 
example, if the fat covers 12 divisions, the fat percentage would be 
.003X12=.036=3.6%. 

The Bogg's method for determining the proteid percentage is very 
simple and requires less than five minutes' work if the phospho- 
tungstic acid solution is previously prepared. It is a modification of 
the Esbach test for albumen in urine and is very accurate. The re- 
quirements are (1) an Esbach tube of the standard pattern reading 
from 1 to 7 gms. per litre, (2) a 2 c.c. pipette, (3) a 20 c.c. measure, 
and the following solution: 

"Phosphotungstic acid 25 gms : distilled water 125 c.c. After 
thorough solution is obtained there is added hydrochloric acid (cone.) 
25 c.c.diluted with distilled water 100 c.c." 



This and the following proteid test can be done readily in the physician's 
office. 



279 

This solution will be good for months if kept in a dark bottle. The 
milk should be diluted with water 1 :10 (cow's milk should be di- 
luted 1:20). With this diluted milk, fill the Esbach tube up to the 
mark IT, reading from the bottom of the meniscus. Add phospho- 
tungstic acid, solution up to the mark R. The tube is corked and 
slowly inverted 12 times. Set aside for 24 hours, when the percent- 
age can be read directly at the top of the precipitate (if the dilution 
be 1 in 20, multiply the reading by 2). 

If the physician is too busy to do this work there is doubtless in 
the vicinity some one who has the time and the technic, just as there 
is some one who can do urinalyses and blood examinations. In the 
present day, this analysis, with the comparatively simple technic 
at one's command, should certainly be done, and one has only to read 
the pages of Rotch, giving his experiences, to be convinced. He 
gives analyses of breast milk on which babies are not doing well, fol- 
lowed by analyses after the milks have been changed by exercise, diet, 
et cetera, and the babies doing well. During the interval, it is fre- 
quently best to put the baby on a modified cow's milk, pumping the 
breast at regular intervals to keep up the supply of mother's milk. It 
must be remembered that although the sugar and proteid are constant 
in milk taken from a breast at a given feeding, the fat is very low at 
first (1% to 3%) gradually increasing to the end of nursing to 
6% to 8% (Tayler- Jones). The writer has found it at the end as 
high as 16.8%. 

There are reasons, however, for taking the infant off the mother's 
milk. Engel (Pfaundler and Schlossman) says that the presence of 
tuberculosis in the mother is the only absolute contraindication. This 
may be considered as going somewhat to an extreme, but certainly it is 
not necessary as frequently as was formerly thought. In mastitis for 
instance if there are no pus cells in the milk the baby should be put to 
the breast. If there are such it may be that a temporary change only 
is necessary. In eclampsia, babies have thrived well on mother's milk 
when at first for a few days other provisions had to be made for them. 
The menses need not interfere with nursing. When babies are affected 
at such times, a substitute milk can be given for a few days. 

The care of the breasts should begin early in pregnancy. If the 
nipples are inclined to recede or are not well formed the patient 
should be instructed how to draw them out daily. For one month 
before the expected date of confinement a solution of equal parts of 
water and 95% alcohol, saturated with boracic acid should be applied 
night and morning to the nipples, which then become less tender and 
are less readily infected. Before and after nursing a plain boracic acid 
solution should be used, for bathing the nipples, as well as for wiping 
out the mouth of the infant. 

The new born should be placed to the breast as soon as possible 
after the mother is made clean and comfortable and the baby has been 



280 

cleaned* and dressed. The garments should be very plain, only suf- 
ficient for warmth and comfort and the baby then taken to the mother 
for nursing before either goes to sleep. The longer the delay the 
greater chance there is for the baby losing the instinct of nursing with 

which it is born. More than one baby has been put on substitute f 1 

because, after honrs of delay, its instinct for taking the breast has been 
lost. Water may be given freely during the first three days, before 
lactation is established, but sweetened water is not advisable and 
certainly not sweet weak tea, as suggested by Camerer ( Pfaunder and 
Schlossmann). The time and frequency of breast feeding should be 
somewhat as in the following table : 

Age No. 24 Intervals Night 

hrs. hrs. 

First 2 days 5 4 1 

3rd day to 4th week 9 2 1 

4 to 6 weeks 8 2l/ 2 1 

t> weeks to 3 months 7 21/2 

3 to 5 months .6 3 

5 to 12 months 5 3 

Until lactation is established the nursings should be four hours 
apart during- the day and once at night. The two-hour interval, begun 
with the establishment of the milk secretion should be changed to '2 l /-2 
hours before four weeks have passed, and that to three hours before 
the baby is three months old. As each case has to be considered indi- 
vidually, this should not be done invariably. The night feeding, really 
essential in the early weeks, should be dispensed with as early as 
possible, certainly by the fourth month, and preferably earlier. In 
any case, regularity should be the keynote for feeding, for any other 
course causes digestive irregularities, beside changing the milk can- 
siderably. It is immaterial whether one breast or both breasts are used 
each time, but it is important that the" first breast should be well 
drained first, as this emptying of the breast tends to give a better milk 
supply. The nursing should take place very slowly ; if the breast 
milk flows rapidly, the baby should be drawn away from the nipple 
every few seconds during the first part of nursing. Colic is more 
likely to be due to too rapid taking of the milk than to any food that 
the mother has eaten. Her diet has been blamed for far too many 
troubles of the nursling in the past. Weaning should take place before 
the end of the first year, depending somewhat upon the relation of 
summer to that age. In northern climate it is usually better to nurse 
through the summer months. All children by the- eighth month should 



* For the first three days of life, instead of soap and water the baby should 
be cleansed with a warm, pure sweet oil, preferably olive oil, sufficient being 
left on the skin to be sensible to the touch. This is not so exhausting as the 
soap and water bath, keeps a more even temperature, preserves the delicate 
skin much better, and cleanses thoroughly, except perhaps the hair, on which 
soap and water may have to be used. 



281 

begin to have some other foods prescribed by a physician. As early 
as the third or fourth month one bottle feeding may be substituted for 
a breast feeding in order that the mother may have rest or recreation 
away from the baby. 

Wet Nurse. 

If the mother can not nurse her child, the next best method, of feed- 
ing is from the wet nurse. The choosing of a wet nurse is a responsi- 
bility which should be undertaken only by the physician. She should 
be free from tuberculosis and syphilis, but aside from this, the condition 
of her own child is the most important consideration. It can never 
be told, from the appearance of a breast, whether the supply is 
sufficient or not. This can only be judged by her own child and can 
only be decided by trial. For a young baby the milk should be free 
from colostrum and should not be more than six or seven months old. 
I can not agree with Parish that her moral character, aside from her 
responsibility in dealing with the baby and the household, is of import- 
ance, for no detrimental influences can come to- the baby through her 
milk. If she has been used to house work, — and usually she has — 
she should be given plenty of it to do, for a change to an idle life 
and rich food will so alter the milk that it will be of little value. It 
is often advisable to continue her own child on the breast, for a woman 
who ordinarily gives 1 to l 1 /* quarts of milk a day will, with use, in- 
crease the amount to 3 or 4 quarts. And to take her own baby off the 
breast is defeating the end which is so vigorously advocated. The 
physician's responsibility to the wet nurse is also- to be considered. 
The child that is given to her to nurse must be free from syphilitic taint 
and it is a grave question ' whether any use should be made of a wet 
nurse in foundling asylums. 

Cow's Milks .A Comparison. 

The substitution of some food other than human milk for a baby 
is a serious matter. The fact" that there is such a diversity of views 
as to how this substitution shall be conducted is a recognition of in- 
ability as yet to understand fully the problems involved. It is fairly 
uniformly conceded, however, that cow's milk is the best and most 
practicable substitute in most civilized countries.* 



* Asses' milk undoubtedly would be a very satisfactory milk could it be ob- 
tained, because the proteid forms a jelly-like mass in the stomach rather than 
a curd mass. Goat's milk is especially good because the goat is a more sturdy 
animal than the cow and the milk, therefore, less liable to be affected by dis- 
ease and disposition. 



282 



The average compositions in woman's milk and cow's milk are as 
follows : 

Woman's Cow's 

' Fat 4.00 4.00 

Sugar 7.00 4.50 

Proteid 1.50 3.50 

Mineral Salts 20 .75 

Water 87.30 87.25 

It would seem that, by using water to dilute the proteid of cow's 
milk, by adding milk sugar to increase the total sugar, and cream to 
bring the diluted milk back to a 4% fat, one would get practically wo- 
man's milk, in other words, change from a 4.-4.50-3.50 to a 4.-7.-1.50 
milk. Practically and theoretically both in the stomach and in the 
test-tube they are not the same and the following table will show 
some of the reasons for differences: 



Fat 



Sugar 



Proteid 



Woman's Milk 

3% to 5 %'. 

Finer emulsion. 

More oleic acid. 

Twice as many fat globules 

as in equally fat cow's 

milk. 
Thus more digestible. 

7% 

1.50%. 

Less casein. 
More lactalbumin. 
Forms fine curd. 



i More nuclein. 
Minerals < More lecithin. 

( More organic phosphorus. 



Reaction 



Bacteria 



Fer- 
ments 



Slightly alkaline. 



Few: — theoretically sterile, 
and as it is ingested at 
once is practically so 



Characteristics 
milk. 



of human 



Cow's Milk. 

3% to 5%. 

More volatile acids. 

More difficult to digest. 



4.5% 

3.50%. 

More casein. 
Less lactalbumin. 
Forms large curd. 
More difficult to digest. 

More total phosphorus but 
more inorganic than in 
human milk. 

Amphoteric — 

or acid, according to the 
diet of the cow. 

Many bacteria at once un- 
less the most painstaking 
precautions are used. In 
much marketable milk bil- 
lions of bacteria. 

Characteristics of cow's milk 
and not characteristic of 
human milk. 



There are other difficulties beside these chemical, physical and bac- 
teriological differences already mentioned. The question of infection 
arises — from tuberculosis in the cattle or in man handling the milk; 
typhoid fever and the exanthemata from employees. There are fer- 
mentative and putrefactive changes. Improper feeding of the cattle 
may be very evident in the milk and ill treatment is sure to be ap- 



283 

parent, for the cow is a tender and delicate animal. Yet, given all 
these things satisfactorily, there is a difference which shows that the 
milk of each species of animal is adapted specifically to the young of 
that species. 

Review of Methods. 

It can readily be understood that with all these difficulties facing 
the profession new methods have been continually adopted and dis- 
carded for other new methods and that at present there is a wide 
diversity of opinion regarding proper substitute food for an infant. 
Since this is the case and since such different views are held by the 
most eminent physicians in this line of work, it seems advisable to 
outline the developments of the feeding problem in the last quarter 
of a century. As far back as 1861 Gerhardt in Germany said that 
by the addition of water and sugar to cow's milk it could be made 
like mother's milk, although he held that mother's milk was composed 
of a 2.6 fat, 4.3 sugar, 3.9 proteid. Biedert in 1874 advocated adding 
water and sugar to cream. Yet he said that there was 4% of casein 
in mother's milk, though sometimes only 2% to 2.5%. From his 
researches he emphasized two points, that the casein in mother's and 
cow's milk were different physically and chemically, and that the 
amount in the two milks was different. His principal prescription was 

Cream (composed of 9.5-3.4.) % litre; previously boiled 
water, % litre; milk sugar, 5 gms. (making total of 15 gms.) 

The result he gave as a 2.4-3.6-1 mixture. He had six different 
formulae: the highest fat in any one of them was 3%, the highest 
sugar 4%, and the highest proteid 3.2%. That was in 1874. 

In 1882 Dr. A. Y. Meigs, of Philadelphia, presented a rational 
basis for modifying milk. He said that human milk, from careful 
analyses, contained only 1% of proteid and that cow's milk, therefore, 
to be proper food for a baby, should be sufficiently diluted to lessen 
the proteid to 1%. This, whether applied in the future or not, may 
be looked upon as the first scientific step toward solving a very diffi- 
cult problem. 

Meigs continued his researches and insisted that his results of low 
proteid and high sugar were correct and that those of Yernois and, 
Becquerel, so much quoted, of casein 3.92% and sugar 4.36% in 
woman's milk were wrong. He judged that they, in separating the sugar 
from the proteid, did not get the former all out. Any one who has at- 
tempted to do this bit of physiological chemistry with human milk 
knows that such might readily happen. Two points he maintained 
stoutly, (1) that whatever differences there are in the two caseins 
(woman's and cow's), the quantity of woman's is one-third that of 
cow's and (2) that modifying cow's milk to give the percentages of 
woman's milk, (as his analysis found it, 4.2-7.4-1) one should get 
a prescription that would serve from the time of birth until eight 
months of age. Though he claims no originality in modifying milk, 



284 

he does claim that copying nature had not been done previously be- 
cause no one knew what was the proteid percentage of woman's milk. 
1 1 is prescription was 

Cream 2 parts 

Milk 1 part 

Lime water 2 parts 

Solution of milk sugar 3 parts 

2 to 3 oz. q.2h. 

As cream was usually old, he advised in 1889, when discussing the 
subject, that top milk be obtained by letting it rise in tall pitchers. 
The solution of milk sugar was made by adding 17% drams to a pint 
of water. In this same paper he says that sterilization of milk is not 
necessary in all cases, but is most necessary among the poor. Booker, 
in the discussion, advised sterilizing in summer. Holt called attention, 
in the light of our present knowledge, to an interesting condition. He 
said that frequently the mistake has been made of giving too much and 
too frequently of artificial food, and that he had been examining the 
size of stomachs, with a view to finding out the proper amount of a 
feeding. 

It was soon apparent that the one formula was not, practicable 
because of the different weights and conditions of children, and that 
the same food for a child of eight days and one of eight months was 
quite imj)Ossible. A more flexible system, adapted to the ability of 
the child, was worked out. This came to be known as the percentage 
method of feeding, or, on the other side of the water, as the American 
method. To no one so much as to Dr. T. M. Roteh, of Boston, is 
the world indebted, for the development of this method and the work- 
ing out of the principles involved. The difficulties were innumerable, 
and at times seemed insurmountable, but the results will remain as a 
monument to the father of percentage feeding. His, idea very early 
came to be that, as skilled pharmacists prepared drugs, so should milk 
laboratories be established where educated, clerks, under medical 
supervision, should fill prescriptions for milk modified to exact per- 
centages. This must have seemed impossible to nearly every physician 
at that time, yet in 1891 the first Walker-Gordon laboratory, under 
the care of Mr. G. E. Gordon, was established in Boston. One year 
later a second was established in New York City, and today there are 
21 laboratories* in as many different cities (Roteh, Morse). At 
these laboratories all cases for modified milk have to be on the pre- 
scription of a physician. The advantages of this method were innum- 
erable, both to the mother and the physician. It also placed infant 
feeding where it, should be, — under the physician's care. The two 
objections to it, were expense, costing about 40 cents a day, and the 

* The laboratories have distributing stations at all the principal resorts from 
Bar Harbor to Norfolk. On their 69 different farms there are more than 
4.000 cows, all tuberculin tested. 



285 

manipulation necessary. But if manipulation had to be, it was better 
done with the best of facilities for cleanliness and exactness than in 
Untrained hands. In difficult feeding cases the results were found 
to be much more satisfactory than in any other way, for variations 
from the formula called for were at a minimum and changes of such 
a small percentage as would be impossible in home modification could 
be made. 

Tf expense made the laboratory milk impossible to consider, milk 
could be modified at home less accurately but, in most cases, quite 
satisfactorily. There were many questions which arose regarding 
the creams, sugars, et cetera, to be used,. Cream, as is well known, 
may be obtained either by gravity or by centrifugalization. Certain 
objections had been raised against centrifugal cream, but of the two 
it seemed much preferable because freshness was considered a very 
important quality and gravity cream was 24 hours older. As top 
milk has been coining into use more and more for home modification, 
this agitation over centrifugalized versus gravity cream will drop 
into the background to some extent. Milk sugar and cane sugar each 
had its advocates. Holt, Botch and Morse believed in the former as 
more rational, because the sugar in woman's and cow's milk was milk 
sugar, and because cane sugar fermented sooner. Jacobi was one 
who for years advocated cane sugar instead of milk sugar, because 
milk sugar hastened lactic acid fermentation and so caused quicker 
coagulation with larger curds. In addition it changed into oxalic 
acid (Baldwin) by fermentation in the intestinal canal. A further 
difficulty with the use of milk sugar was its impurity. Proteicl, in 
percentage feeding, has seemed, in the past, to cause the most concern. 
To reduce the proteicl, or at least the curd formed from it, several 
methods have been used. The simplest method was to lessen the pro- 
teid by dilution ; a second was to lessen the casein by adding whey to 
a smaller amount of cream or milk, making the proportion of casein 
and whey more like that in mother's milk (see p. 283) ; a third was 
partly to peptonize or digest by adding pepsin or pancreatin (see p. 
284) ; a fourth, by the use of a cereal diluent to break up the curds (see 
p. 287). The first method has been adopted in routine for a long time. 
For instance, if there had been given a 2.-5.50-2. and it was decided 
that the proteid was too high and that a 2.-5.50-1.75 should be used, 
the change could readily be made. It has been necessary to have 
either a tabulated card* showing amounts of cream, milk, water, and 
sugar to be used or, which is even more satisfactory, to have formula? 
in which, by substitution, one may readily obtain the proper number 
of ounces of each (see p. 292). 

With a formula, one can use the principle of percentage feeding 
without, at the same time, using the high fat percentage which has 
been advocated so much in the past. Holt and others have for several 

* Such tabulated cards have been gotten out, one by Dr. Ladd of Boston, and 
one by Dr. Westcott, of Philadelphia. 



2S6 

years advocated lower fat and higher proteid modifications and the 
results justify the change. 

Roteh has said that to use modified milk without knowing the per- 
centages was like running a ship without a compass. This is so true, 
and the satisfaction that comes of knowing them well repays one for 
figuring it out. In the end it is really a simpler method. It is much 
more intelligible to have a physician state that he is using a 2.-5.50-0.75 
with eight feedings of 3 ounces each than to say he is using 2 1 /2 ounces 
of a 16% cream, 2 ounces of skim milk and 1 ounce of milk sugar 
in a 24-ounce mixture. One has, in the former, a basis on which to 
compare it with other cases ; one has a compass as guide. 

Whey mixtures. — Piroteid in milks is composed principally of 
casein and lactalbumin (curds and whey) in proportions as follows 
(Konig) : 

Casein Lactalbumin Proportion 

Woman's 0.59 1.23 1 :2 

Cow's 3.02 0.53 6:1 

This gives approximately a proportion of 1 :2 in woman's milk and 
6 :1 in cow's milk. There is much more casein to coagulate in cow's 
milk, in proportion, and whey* has been added to milk mixtures to 
make the proportion of casein and lactalbumin like that in woman's 
milk, 1 :2. Whey mixtures have been used for very young infants — 
premature or during the early days of life — in acute indigestion cases, 
and in certain other feeding cases. As the casein had to be reduced 
to a minimum, a small amount of rich cream had, to be used with 
whey as part or all of the diluent. For exact directions see Rotch. 
The whey should be heated to 150°F. to destroy the rennet ferment 
before the addition of the cream which would otherwise be coagulated. 

Alkalinity. — Since human milk is alkaline, it has been supposed 
that, to make cow's milk as much like human milk as possible, some- 
thing should be added to cause a slight alkalinity. The majority of 
writers in this country have used in the past, and, indeed many of them 
are today using, lime water* for this purpose. Jacobi has never ad- 
vocated any alkaline addition: he does not approve of lime water and 
makes a strong protest against bicarbonate of soda. The idea seemed 
to be to delay coagulation in order to make the curd finer. On the 
other hand, it may delay coagulation until the food is carried on into 
the intestine, thus preventing peptic digestion and acting adversely 

* To make whey: Into a clean saucepan put 1 pint of fat-free milk. Heat 
to 100° P. and add 2 teaspoonfuls of essence of pepsin, liquid rennet or a 
junket tablet; stir sufficiently to mix. Allow to stand until firmly coagu- 
lated. Break up with a fork and strain. The whey (liquid part) is ready 
for use. Keep cool. 

* To make lime water: Place a piece of unslaked lime the size of an egg 
in a gallon of water in an earthen jar or glass bottle. Stir and let settle. 
Pour off this first water and add fresh. Use from this. Replenish by adding 
water. 



287 

on intestinal digestion because chyme coming from the stomach under 
this condition is alkaline instead of acid. This danger is of course 
at a minimum but it is a question (White) if the curd is made finer 
by adding the lime water. 

Peptonized milk. — A partial digestion of the proteids of milk in 
order to relieve the stomach of some or most of its work has seemed 
necessary in some cases. It has been used in acute indigestion and in 
chronic cases where some relief from work has been necessary for 
the stomach. It should be used very discreetly and should not be 
used for any length of time. The method of making it is as follows : 

Milk 1 pint. 

Water 4 oz. 

Bicarbonate of soda 15 gr. 

Extractum pancreatis 5 gr. 
To peptonize partially, heat to 105°-115°F. for ten minutes and place 
on ice until used,, for the cold will check the digestive process. To 
peptonize completely, heat for two hours, but as this is very bitter, 
it is not often used. 

Sodium citrate. — Wright in 1893 suggested the addition of sodium 
citrate to cow's milk to make it a "humanized milk" so far as the lime 
salts were concerned. His argument was that (1) rennet coagulation 
is less firm if some of the lime salts become precipitated as insoluble 
salts, (2) since human milk contains 0.03% lime salts and cow's milk 
0.17%, much of that in cow's milk should be made insoluble, (3) 
sodium citrate added to plain milk will do this. He advocated its 
use especially in the treatment of dyspeptic conditions. Though not 
extensively followed, it has been used in healthy as well as in sick 
infants. 

Diluents.- — The most common diluent for modifying milk is boiled 
water. There are many, however, who believe that a cereal diluent 
should be used even in very young babies because the starch acts on 
the proteid — probably mechanically— prevents a hard coagulum and 
thus aids digestion. Jacobi has held this view for more than 40 years. 
On the other hand,, there are those who hold that as woman's milk 
does not contain starch, it should not be used, during the first 10 to 12 
months. It can undoubtedly be used to advantage in many cases after 
the fifth month. Methods for making the gruel or water are as follows : 

Barley water. — Make 2 tablespoons of barley flour into a thin paste, 
stir in 1 quart of water. Boil 15-20 minutes. Strain. This is used 
in acute conditions in place of water when milk must be omitted. 

Bice water. — Make as barley water, using 2 tablespoons of rice 
flour instead. Or use rice, cooking slowly and adding continually up 
to 1 quart. This is useful in diarrhoeas. 



288 

Oatmeal water. — Stir 2 tablespoons of oatmeal into 1 quart of boil- 
ing water. Cover and allow to simmer for 2 hours. Replace the water 
as it evaporates. Strain. Useful in constipation. 

Dextrinized Gruel. — Chapin advocates dextrinated gruel, believing 
in many cases that its action as a diluent is more satisfactory than 
the simple gruel or water, because the sugar can be digested by the 
infant better than the starch and the action of breaking up the curd 
is just as satisfactory. He makes it by adding to the gruel already 
cooked and cooled, but not strained, 1 teaspoonful of disastase solution.- 
Stir and strain. The disadvantage in this is that there is no chance 
for developing the amylolytic digestive functions, as there is in using 
simple gruels. 

Butter milk or acidified milk. — Butter milk has been used in Hol- 
land for infant feeding for about a century and, a half, and was popu- 
larized first by the peasants. From Holland its use has spread to 
many other countries as a food for infants. It is composed of a 
0.50 fat, 3.0 sugar, 2.50 proteid, or about that, and as a food, there- 
fore, supports the theory of calories. It contains .34% of lactic acid. 
It is probably more useful in cases requiring a low fat percentage 
and high proteid percentage in a very readily digested, form. Bagin- 
sky considers it a specific in dyspepsia. It is not ordinarily used raw 
but cooked with sugar and flour (see Morse). 

In foreign countries the percentage method has been used only to 
a small extent. In England it has been advocated, quite a bit but 
hardly at all in France. They have been using simple dilutions and 
strong ones, as much as plain milk and water equal parts, for a baby 
of two weeks. Budin prefers whole milk sterilized, but small quanti- 
ties with few feedings. In Germany the dilution of half each is not 
reached until the baby is about two months old (Camerer). In Ger- 
many they have had also a milk modified by what is known as the 
Gartner process.* Its use in this country has never been advocated. 

Another method, inaugurated by Heubner and which has a large 
following, especially in Germany, is a milk based, on the number of 
calories a baby should receive in 24 hours. Some time previously 
Biedert advocated the smallest amount of food necessary for normal 
increase in weight, but Heubner determined 'the number of calories 
per day per kilogram of body weight a breast-fed baby should get in 
order to develop properly. This energy quotient he found was about 
100 calories for from three weeks of age to six months, and from six 
months a gradual decrease to about S5 calories at the end of the first 
year. The overfeeding which had existed previously could be pre- 

* This is as follows: Dilute milk at cow heat (36°C.) with an equal quan- 
tity of warm boiled water; pass the mixture through a centrifuge, so ad- 
justed that the tubes for the cream and skim milk carry off equal quantities. 
The cream is the modified milk and contains 3-2.50-1.70 and so requires about 
5% of sugar added. Of course the fat varies with the fat percentage of the 
natural milk. 



289 

vented in this way. This was especially brought out by Czerney and 
Keller. They showed that the difficulty in ordinary feeding was not 
the proteid, which is readily digested, but the excess of fat. As a 
result they have gone somewhat to the other extreme and advocated 
fat-free milk. Just why an infant born with a lipolytic ferment for 
splitting fats in its duodenum should be given a food entirely free of 
that element is hard to be understood. That very little fat can be 
digested by certain babies is, however, readily recognized. 

The opinions seem to be, after twenty-five years, more diverse than 
they have been at any time during that period. The effort to modify 
cow's milk to make it like human milk has not always, even in the 
best hands, been successful. The adding milk sugar and decreasing 
the proteids, adding whey and adding lime water, — the reason for 
each carefully and scientifically worked out, — has not met the re- 
quirements of many cases. In other words, the simple chemical ful- 
filment without the physiological does not make cow's like human 
milk. This has undoubtedly been emphasized in great part by a too 
high fat percentage and, therefore, by a too high energy quotient. 
The other extreme of fat-free milk (probably a 0.50% fat), though 
most valuable in many cases, can not be advocated as a routine diet. 
The problems are still before us ; probably the only way to do at 
present is to have an understanding of all the theories, know something 
of the practices, study the baby as an individual and apply as the 
study of the case indicates. Above all it must be remembered that 
babies can not be fed by rule. 

The Simple Feeding Case. 

For some time the writer has been using very simple formulae for 
the average feeding case. The first essential is good fresh milk from 
a mixed herd of tuberculin tested cattle, preferably from the more 
robust breeds of Holstein, Durham, and Ayrshire. The milk should 
be of the class called certified milk, if such can be obtained. The 
three most important essentials are sterilized vessels, including the 
milking pail, bottling on the farm and a low temperature (40°F.) 
from immediately after milking until delivery to the consumer. If 
poor or unknown milk must be used it should be pasteurized at 60 ° C. 
(140°F.) for 20 minutes (Kosenau). In the heated summer months 
most milk should be pasteurized at 60°C. for 20 minutes. With 
fairly good milk the best time for pasteurizing is immediately before 
using, unknown milk earlier in order that toxins may not develop. 
Certified milk ought never to need pasteurization. 

The utensils and other things necessary for modifying milk are : 

Chapin cream clipper (when needed). 

A pitcher for mixing. 

An 8-oz. glass graduate. - . . 

A funnel. 

Feeding bottles. 



290 

Rubber nipples. 

Bottle brushes. 

Pasteurizer (or double boiler). 

Sterilizer nonabsorbent cotton. 

Boracic acid. 

Milk sugar or cane sugar. 

Lime water (when needed). 

Boiled and boiling water. 

Bottle of milk. 
Utensils used should all be washed well, rinsed well, and then 
scalded and drained but not wiped. None of these things should be 
used for other purposes. If cream is to be removed from the top, the 
first dipperful (this holds % oz.) will have to be taken off with a 
spoon; the rest can be removed by the dipper. The nipples must 
be simple and the kind that can be readily turned for cleaning. 

The plain milk of 4. fat, 4.50 sugar, 3.60 proteid is used ordinarily. 
By division into eighths and using some eighths of milk and the rest 
of the eighths water (adding sugar to give the desired sugar per- 
centage) there results a simple and practical method, with known 
percentages and one that is satisfactory in the average simple feeding 
case. For example, one-eighth milk gives fat .50 and proteid .45, so 
that one-eighth of plain milk in seven-eighths water, previously boiled, 
gives a very weak formula. It is wise, however, to begin on a low 
percentage formula, for the ultimate progress is then more assured. 
A three-eighths milk and five-eighths water results in a 1.50 fat and 
1.35 proteid, which with eight teaspoons (1 oz.) of sugar to the 20 
oz. mixture, gives about a. 5.50% sugar. The resulting modification 
is a 1.50-5.50-1.35. The necessity of keeping the percentages in mind 
must be emphasized for this is the only satisfactory way to work 
intelligently on substitute milk feeding. Not only the age and weight, 
but the vigor of the child, must be considered when deciding what 
strength should be used, but by two months most babie& may safely 
be put on a 2% fat-1.80% proteid diet (% plain milk and i/2 water). 
The fat percentage may have to be lowered and this can readily be 
done by removing top milk before the milk to be used is mixed. An 
addition of 1 oz. of milk sugar to a 20-oz. mixture adds approxi- 
mately 4% of sugar. The frequency and number of the feedings 
should be the same as in breast feeding (see p. 280). The amount 
at two months should be about 3 or more ounces for the average child 
of average size; at six months about 6 oz. or less; and at eight or 
nine months about 1 oz. This should depend, not only on the size and 
weight of the baby, but cognizance of the number of calories in the 
24-hour mixture should be taken into account. 

Taking a 2.-6.-1.80 mixture with eight feedings of 3 oz. each for 
a two-months-old baby weighing 10 lbs., the following results in 
calories are obtained: 



291 



8X3=24 oz.=768cc or gms. 
10 lbs.=4539.9 gms. wt. 



2 % fat X 9.3=183 cal. 
6% sugar X 4.1=246 cal. 
1.8% proteidX4.1= 73.8 cal. 

502.8 calories per 1000 gms. of feeding which 
is the same as 385 calories per 768 gms. of feeding (the amount of 
feeding used for this baby) ; 385 calories for a baby weighing 4539.9 
gms. is the same as 85.5 calories per 1000 gms. wt. 

As, according to Heubner, 100 calories per kilogram per 24 hours 
may be allowed during the first three months, it is seen that a 2.-6.-1.80 
mixture of 25 oz., making only 85 calories for a 10-lb. baby, may be 
increased, either in strength, in number of feedings, or in amount in 
each feeding. The individual case must be the guide. That the 
caloric value is the only point at issue certainly can not be recognized 
as true, though as an adjunct to percentage feeding it should be of the 
greatest assistance. In each one of my feeding cases I know the 
caloric value and consider it an excellent guard in modifying milk. 
It is also of assistance in deciding when to increase a baby's food, 
for it is not desirable to increase the food, if the baby is gaining, 
but, on the other hand, one does not wish to wait for a, loss in weight 
before learning that it is time to increase the diet. 

More Difficult Cases. 

There are several indications for changing a baby's food. If there 
is colic the food should be given more slowly, perhaps less of it, 
and the stools watched. If there is much fat in the stools, the fat 
percentage should be decreased. Vomiting immediately after feeding 
suggests a necessity of decreasing the amount of food ; if sour masses 
come up it may be due to one of several causes, such as too acidf a 
food or too fat a food (see p. 278). If the regurgitation comes an 
hour and a half to two hours after feeding, it may be necessary to 
help the digestion by peptonizing the food (see p. 287) or the aid 
may come in one of several ways. At any rate it is a case for study 
and may be looked upon as a difficult feeding case. Each one of 
these difficult cases is of necessity a study, and, at times, a grave 
one. With them, the simple method just described of using eighths 
of a whole milk does not prove satisfactory and here the accurate 
percentage method comes into play. In cases where changes have to 
be made in .05% and that only in one element at a time, the Walker- 
Gordon laboratory is the only salvation. In most difficult cases it is 
a greater aid to the physician, who can feel surer of the accuracy 
of the food. Otherwise he must calculate fractions of percentages 
and keep his method for calculating the formulae by him. A very 
careful history of the infant must be obtained in order to decide the 
nature of the trouble; whether a chronic indigestion, a feeble di- 
gestion, or a difficulty that lies wholly in the intestines. One can 
learn of pitfalls already encountered and avoid them. One may be 
able to gain some knowledge regarding the element in the food that 



292 

was giving- the trouble. After all this has been learned and the per- 
centages decided upon for the home modification one must express it 
in ounces of each ingredient for the benefit of the mother or nurse 
who is to have the care of the child. There are many ways of figuring 
it out, for many methods for calculating the amounts have been pub- 
lished. The simplest one I know that is entirely elastic, — and it is 
truly simple, — is Baner's as follows: 

Q=Quantity desired (in ounces). 

F=Desired percentage of fat. 

S=Desired percentage of sugar. 

P=Desired percentage of proteid. 

C=Cream. 

M^=Milk. 

Cream in oz.= — --^ X (F — P) 

Percentage of fat in cream — 4 

Milk in oz.= QXF — C ' 

4 

Water=Q— (C+M) 

Dry Milk Sugar = ( S ~ P )XQ 
J 8 100 

To illustrate, take a 1.50-5.50-1.25, 24 oz., using a 16% cream. 
It may be obtained by substituting these values in the above equa- 
tions thus: 

24 

Cream= X(l-50 — 1.%5)=V» oz. cream. 

16—4 v } /z 

Milk= 24X1 - 25 -V 2 =7 oz. milk. 
4 

Water=24— (l/ 2 + 7)=16% oz. water. 

Tir'-n o (5.50— 1.25) X24 

Milk bugar = — - =1 oz. milk sugar. 

6 100 & 

So we have to give to the mother or nurse this formula : 
Cream y 2 . oz. 

Milk (fat free) 7 oz. 
Water 16% oz. 

Milk Sugar 1 oz. 



24 oz. 



Careful instructions should, be added as to how much to put in 
each bottle and how frequently the child should be fed, and if at 
all during the night. In addition, if this is your first instruction 
to her, see that she understands about the utensils and the care 
necessary. 



293 

In these difficult cases, where it is not practicable or possible to 
have a wet-nurse for every feeding, it is worth an effort to get one 
for one or two feedings a day. This is done on the principle that 
ferment-like bodies secreted from the human blood through the milk 
provide these ferments in the infant's blood, and supposedly give a 
greater bactericidal power to it. At any rate, the bactericidal power 
is there. 

The premature infant presents an especially difficult problem. 
There are so many side issues of importance. The incubator, which 
was formerly considered, so necessary, has been discarded by many. 
It has two very striking objections: the difficulty of keeping the 
temperature at a proper level, and the lack of fresh air. Either is 
enough to make one feel that pillows, blankets, and hot water bags 
are preferable. The best method of keeping the temperature of the 
little one at normal heat is an electric pad. They can be turned on 
to three different degrees of heat and are admirable. The oiling of 
a baby, instead of washing, is most important and absorbent cotton 
should be used in place of a napkin. It is not advisable to use this 
cotton all over the baby, for in moving their hands the fine, thready 
pieces are very liable to get in the mouth. Where breast milk 

can not be obtained even for one or two feedings one has truly a 
difficult problem. The stomach can usually hold about one-half ounce 
of a milk modified to a very low percentage. The frequency of feed- 
ing has to be a matter of experiment, but usually every one and one- 
half hours during the day and three to four hours at night suffice. 
I had one baby (of 2 lbs. 1 oz. weight) who would sometimes go 
longer without feeding during the night. The kind of milk, whether 
a whey mixture as- advocated by one school, or the other extreme, 
fat free, plain milk, as advocated by another, must be decided accord- 
ing to the surroundings, the facilities, and the infants. 

Pasteurization, Boiling, and Sterilization. 

Years ago many physicians found that boiled milk agreed with 
babies much better than raw milk. It would keep better, too, and 
not sour so readily. More than forty years ago Jacobi advocated it. 
Since then there has come to be some understanding of the bacteria 
that caused the trouble and how boiling (sterilizing, as they called it) 
helped the difficulty. Since then, too, Pasteur has added to the 
knowledge of heating to destroy germs and a similar process has 
come to be known by his name. 

Pasteurization of milk is the heating of it to between 60° and 85°C. 
(14rO°-185°F.), followed, by rapid cooling. This destroys such patho- 
genic organisms as occur in milk and the rapid cooling, a most, 
essential part of the process, prevents the rapid proliferation of such 
spore-bearing and other organisms as may be present in the milk 
and not destroyed, by the heat. Boiling is heating to 100°C. (212°F.) 
and destroys all bacteria that are not spore bearing. Sterilization is 



294 

the destruction of all germs and spores of germs. This requires an 
autoclave or simple boiling on three successive days. The cause for 
the use of all these methods as applied to milk is due to the excessive 
growth of bacteria in this medium and the readiness with which 
they attack it. 

Milk as it comes from the gland is supposed to be sterile. This is 
the exception, however, rather than the rule. Of 25 nursing women 
Ringel found only 3 of the milks sterile. In 17 he found staphylo- 
coccus pyogenes albus, in 2 he found staphylococcus pyogenes aureus, 
in 1 he found both organisms, and in 2 he found staphylococcus 
pyogenes albus and streptococcus pyogenes. There were no patho- 
genic symptoms, but such would hardly be expected since these organ- 
isms are found normally in the mouth. In cow's milk, because of 
the handling, transportation, et cetera, the number of bacteria are 
counted more by the thousands and millions. When one bacillus, 
under favorable circumstances for growth, say a temperature of 
100°F., in 24 hours becomes 17,000,000 it is not to be wondered at 
that milk has done much harm. If milk containing 3,000 germs per 
cubic centimeter be kept (Chapin) : 

(1) 24 hours at a temperature of 86°F. it will contain. . .1,400,000 

(2) 24 hours at a temperature of 60°F. it will contain. . . 800,000 

(3) 24 hours at a temperature of 42 °F. it will contain. . . 2,600 

(4) 48 hours at a temperature of 42°F. it will contain. . . 3,600 

(5) 96 hours at a temperature of 42°F. it will contain. . . 500,000 

This suggests that wonders may be wrought by cleanliness, properly 
applied, and refrigeration. There are also the pathogenic organisms 
to be considered. Innumerable epidemics have been traced to the 
milk supply (Swithinbank & Newman), (Trask). 

In considering the raw and pasteurized product, boiled and steri- 
lized milk will not be touched upon. There are several reasons why 
pasteurized milk is advocated by some authorities. This process 
destroys all pathogenic organisms, it destroys the greater number of 
the many other bacteria present and, as a result, it has lessened the 
mortality from gastro-intestinal diseases among children. These are 
all good reasons and any one of them is sufficient to convince one of 
the necessity of heating if these difficulties enumerated could not be 
eliminated as a part of the milk and if there were no objections to 
pasteurized milk. Pathogenic organisms can be and are kept out of 
milk and a large bacterial count has been demonstrated as unnecessary 
if certain precautions are taken. The use of pasteurized milk has 
been vigorously opposed by most pediatrists, for routine, because of 
bad effects which they believe they have seen from its use in children 
under their care. It is accepted that pasteurizing milk causes the de- 
struction of the lactic acid bacteria (thus preventing milk from sour- 
ing so that old milk remains apparently good longer), it destroys 
the lecithin, it changes the sugar and partly destroys it, it makes 
some of the calcium salts become insoluble, it is injurious to certain 



295 

ferments and destroys the germicidal property of milk. Whether 
rickets and scurvy have been caused by heating of milk — as held by 
many authorities — can not be settled now, but it is true that more 
eases are found among babies fed on pasteurized milk than on plain 
milk, and more among those fed on boiled milk than on pasteurized 
milk (Holt). And it is also true that they recover from these dis- 
eases when taken off the pasteurized or boiled milk. In addition, 
Doane and Price proved conclusively that raw milk fed to calves 
was more digestible than pasteurized or cooked milk and that cooked 
milk caused violent scouring in the majority of trials. 

It is unquestionably true that poor or unknown milk can do more 
harm raw than pasteurized and all such should be heated to 60 °C. 
(140°F.) for 20 minutes. Pasteurized milk can do much harm 
through the carelessness with which it is treated, and as education 
is necessary it will certainly be best, to educate the public in the right 
way, so that they will demand good milk. In the meantime the bulk 
of milk in most cities should be pasteurized where it has to be used 
for infants. But the effort of every baby's family and physician 
should be to provide for it from that other portion of the milk supply 
which carries no menace with it in the raw state. Such can be found 
in every large city even this early in the crusade against poor milk. 

Charities and Mjjnicical Control. 

The bettered feeding conditions that have been brought about 
through individuals, charity organizations and municipal interest 
should at least be mentioned. 

Probably no country has a finer record of infant life-saving insti- 
tutions than America. Such places as the long pier at Chicago, the 
floating hospital at Boston, the seaside fresh air homes near New 
York, and the Thomas Wilson Sanatorium near Baltimore, with 
their fresh air, hygienic surroundings, and feeding under the physi- 
cian's directions, save many baby lives each year. Dr. Coit, of 
Newark, N. J., through his effort to have good milk, has done much 
not only for the infant and the community, but for the physician. 
Probably no one has done a greater work than Nathan Straus, of 
New York. It was in 1892 that he discovered the existence of what 
he called "permitted murder." He believed the large infant mortality 
due to bad milk and started one milk depot which fed one thousand 
children. Any physician doing work among the poor could get it. 
All milk, besides being of the best quality to begin with, is pasteurized 
and distributed only within twenty-four hours of pasteurization. In 
all these intervening years the mortality has decreased and the work 
has grown so tremendously that it must indeed be a great tax finan- 
cially to even a very large purse. But think of looking forward to 
having as a monument in one's old age living beings, — thousands of 
men and women — who otherwise would, have died in infancy ! 

Cities, through the activities of such individuals, are taking an 



296 

interest in the milk question and are coming to regulate the sale of 
this product more and more. There will undoubtedly be a reforma- 
tion in the next few years and we will see milk universally inspected 
just as today meat must be approved for interstate trade. 

Summary — 1. Infant mortality rate is higher than it should be 

2. Breast feeding gives so much more satisfactory results in a 
baby that every effort should be made to keep it on the mother's milk. 

3. One breast feeding a day is urgently needed if a substitute 
food must be used. 

4. Modifying cow's milk to get the same percentages of elements 
as in woman's milk does not give the same result because of chemical 
and physiological differences in the elements of the two milks. 

5. The percentage method of feeding is the most satisfactory be- 
cause it gives one a basis to work on. 

6. The energy quotient is a most important adjunct, not only in 
giving a modified milk, but in deciding when to increase the food. 

7. The law should require milk inspection. 

8. In the meantime, poor and unknown milk for babies should be 
pasteurized at 60 °C. for 20 minutes, though every effort should be 
made to provide an infant with healthful raw milk. 

9. In the whole feeding problem the physician has to keep con- 
stantly in mind the fact that each baby is a law unto itself. There 
are certain broad principles not yet completely worked out and classi- 
fied, but the individual baby can not be fed by rule. 



297 



CHAPTER XV. 

MILK PRODUCTS IN THEIR RELATION TO HEALTH. 

In this chapter no attempt will be made to discuss the technical 
methods for the manufacture of butter, cheese, condensed milk, milk 
powder, ice cream, koumiss, kephir and other milk products. The 
methods of their manufacture belong quite outside the range of a 
volume on milk inspection. It is believed, however, that a brief 
account of the relation of these products to human health may be in 
place in this volume. Milk products may retain some or all of the 
contaminations which were present in the milk from which they 
were made. The extent to which these contaminations persist in the 
final products of milk depends in large part upon the processes which 
the milk undergoes in manufacture and upon the elements of the 
milk which go into the composition of the final product. 

Standards. 

It seems necessary in discussing this matter to refer briefly to the 
standards and definitions which have been set up for butter, cheese, 
condensed milk and other products. The standards followed in this 
connection are those adopted by the U. S'. Department of Agriculture 
in its work of examining food products. 

Skim milk is milk from which a part or all of the cream has been 
removed. It differs from blended milk which may have been skimmed 
by centrifugal machines and later received a definite and stated per- 
centage of fat. According to the U. S. standard, skim milk should 
contain not less than 9.25% of milk solids. 

Buttermilk is the product that remains when butter is removed 
from milk or cream as a part of the process of churning. An arti- 
ficial buttermilk is much used,, particularly in the South, and consists 
for the most part of sour skim milk to which small quantities of whole 
sour milk have been added, after which the mixture is agitated to give 
it the appearance of buttermilk. There is nothing about the composi- 
tion of artificial buttermilk or the method of its preparation which 
should render it any less wholesome than true buttermilk obtained in 
the process of churning. 

Condensed milk or evaporated milk is milk from which a consider- 
able portion of water has been evaporated. It is impossible to specify 
in the short definition of condensed milk the percentages of its various 
constituents for the reason that these vary so greatly in the processes 
of different manufacturers. The process of evaporation is carried on 
longer by some manufacturers than others and in some cases a part 
of the cream is removed while in others this is not the case. Moreover 
cane sugar may be added to condensed milk to the extent of 40% or 



298 

more, which will appear in the analysis in addition to the milk sugar 
normally present in milk. 

Milk fat or butter fat is the fat normally present in milk. The U. 
S. standard for milk fat requires a Reichert-Meissl number not less 
than 24 and a specific gravity not less than 0.905 at a temperature of 
40 degrees C. The term cream is used to mean that portion of the 
milk rich in butter fat which rises to the surface of milk on standing 
or is separated from it by centrifugal force in the operation of 
machines. Standard cream should contain not less than 18% of milk 
fat. Evaporated cream is the term used to denote cream from which 
a considerable proportion of its water has been evaporated. 

Butter is the product obtained by gathering in any manner the 
fat of fresh or ripened milk or cream into a mass and also contains 
some of the other milk constituents with or without salt and occasion- 
ally coloring matter. The U. S. standard for butter requires the 
presence of 82.5% of butter fat. Renovated or process butter is a 
product obtained by melting and re-working butter without the use 
or addition of any chemicals or substances except milk, cream or salt. 
According to the U. S. standard renovated butter should contain the 
same amount of fat as standard butter, namely 82.5%. 

Cheese is the solid ripened product obtained by coagulating the 
casein of milk by means of rennet or acid with or without the addi- 
tion of ripening ferments, seasoning or coloring matter. Whole milk 
or full cream cheese is prepared from milk from which no portion of 
the fat has been removed. Skim milk cheese is made from milk from 
which some of the fat has been removed. Cream cheese is made from 
milk and coram or milk containing not less than 6% of fat. Accord- 
ing to the U. S. standard whole milk or full cream cheese shall con- 
tain in its water-free substance at least 50% of butter fat. 

Hygienic Relations. 

Cream. — If milk is allowed, to stand so that the cream rises to the 
surface by the gravity separation of the constituents of milk, fat 
globules collect upon the surface and in rising carry along with them 
certain amounts of sugar and the salts of milk as well as some of the 
bacteria with which the milk was contaminated. The cream of in- 
fected milk may therefore contain such pathogenic bacteria as are 
found in the milk from which it was removed and these bacteria 
retain their virulence in cream practically as long as in milk. Ac- 
cording to analyses made by Koenig, cream obtained by gravity 
separation contains 26% of fat and according to analyses by Veith 
oream obtained by centrifugal separation contains 50% of fat. The 
cream offered upon the market ordinarily amounts to about 10% of 
the volume of the milk but may exceed, 20%. The amount of fat 
required to be present in market cream is regulated by state and 
municipal laws and varies considerably. As a rule the standard 
requires about 18% of fat. 



299 

Shim milk. — This product is not as extensively sold in this country 
as in Europe. Wherever skim, milk is offered upon the_ market the 
legal regulations usually require that it shall be labelled as such and 
as a rule the requirement of total solids in skim milk is about 9%. 
The wholesomleness of skim milk obviously depends upon the condi- 
tions under which- the milk was drawn and the treatment which it 
subsequently receives. The pathogenic and other bacteria which 
may have gained entrance to the fresh milk remain in about the same 
proportion in skim milk and the conditions for their growth and 
multiplication in skim milk are favorable. If skim milk is to be 
obtained in a sweet condition it is practically necessary that it be 
separated by centrifugal machine since the creaml will not separate 
by the gravity method until considerable time has elapsed,, usually 
sufficient to allow the lactic acid bacteria to multiply to the souring 
point of milk. 

Butter. — Numerous investigations have been made to determine 
the possibility of the growth of pathogenic bacteria in butter and 
the length of time during which these organisms retain their viru- 
lence in butter. It has been shown by Laser that cholera bacilli which 
have gained entrance to butter may remain virulent for 32 days and 
typhoid bacilli three or four weeks. If the virus of plague gains 
entrance to butter it remains in a virulent condition for two months 
or more if the butter is kept at a relatively low temperature. 

Different investigators have determined somewhat different periods 
for the duration of the virulence of tubercle bacilli in butter. 
Thus Moore found active tubercle bacilli in butter 90 days old and 
Gasperini in butter 128 days old. In a number of samples of butter 
which were examined by the German Imperial Health Office the 
tubercle bacillus was found in 32% of cases. There is no satisfactory 
evidence regarding the transmission of tuberculosis to human beings 
in butter but it must be considered as probable that the disease can 
be transmitted in this way, especially in view of the fact that tubercle 
bacilli remain sufficiently virulent in the butter to infect guinea pigs. 
In an examination of the butter from 36 creameries, Teichert found 
tubercle bacilli in that from eight of the creameries. The bacilli 
appeared to lose their virulence after about three weeks. A large 
number of other organisms were also present in butter, including 
lactic acid bacteria., yeast and various species of molds. 

According to observations by Obermuller, the action of pathogenic 
bacteria is much intensified by the presence of butter fat. In his ex- 
aminations a large proportion of butter samples contained tubercle 
bacilli. In one instance each of 14 samples taken in Berlin contained 
bacilli of sufficient virulence to kill guinea pigs when inoculated into 
them. Another species of acid-resistant bacteria often occures in 
butter and may be mistaken for the tubercle bacillus unless inocula- 
tion experiments are made. It appears that the milk of tuberculous 
cows is not fit for use in the manufacture of butter unless previously 



300 

pasteurized and a large number of investigators have recommended 
this procedure. 

It is unnecessary to review in this connection all of the numerous 
articles which report the examination of butter for tubercle bacilli, 
the relative virulence of the bacilli in butter and the duration of their 
virulence. As a general proposition it may be stated that tubercle 
bacilli are found much less frequently in butter than in milk. 

The effect of the feed consumed by the cows upon the appearance, 
composition and flavor of the butter has been extensively studied. 
In some instances the disagreeable flavors in butter have beeu traced 
directly to the use of unsuitable feed stuffs. This is particularly the 
case where cows are allowed to consume plants with striking pungent 
flavors or odors, which persist in the milk and cream. 

The firmness of the butter may be greatly modified by the ration 
fed to the cows. This is a matter which does not concern the whole- 
someness of the product, but complaints are sometimes made regard- 
ing the soft character of the butter. Bartlett and others have found 
that gluten meal and, gluten feed have the effect of producing a soft 
butter and should therefore not be used in too large quantities. If 
feeding stuffs containing a high percentage of oil are given to cows 
the butter may show the specific effect of these oils. Thus it has been 
found that cottonseed oil may be readily detected in butter from 
cows which have eaten large rations of cottonseed or cottonseed meal. 
Similarly with cocoanut oil when this constitutes a part of the ration. 
The presence of the cocoanut oil in the butter affects the Eiechert- 
Meissl number. It is unwise, however, to put too much dependence 
upon the variations which are noted in the Kiechert-Meissl number 
for the reason that this has been found to vary from 24.44 in August 
to 32.02 in February. 

The butter from cows fed, on young fresh grass, clover and other 
succulent material commonly shows a decidedly higher percentage of 
volatile fatty acids than butter from cows fed with dry rations. 

Doane carried on experiments to determine the cause of mottled 
butter. It was found that this abnormal appearance occurred more 
frequently in butter which was imperfectly worked. None of the 
various samples of butter which were worked for four minutes showed 
any mottling. Apparently the cause of mottling in this case was 
the uneven distribution of the salt. The appearance of the mottled 
butter was not up to market standards but the butter was not in any 
way deficient in wholesomeness. Occasionally it is believed by other 
investigators that mottled butter may arise as a result of ripening 
cream at too high a temperature, the use of excessive amounts of cold 
water, insufficient washing and unequal temperature. 

According to Duclaux butter fat may be affected by the growth of 
bacteria and molds. The water content of butter infected with molds 
mav increase with age if the butter is exposed and. the amount of acid 
may be diminished simultaneously. In a study of mottled butter in 



301 

New York by Van Slyke the conclusion was reached that the appear- 
ance is due primarily to the presence and uneven distribution of 
buttermilk and secondarily to the hardening effect of the salt brine 
upon the casein in the buttermilk. It was found that the appearance 
of mottling could be avoided, by stopping the churning process when 
the butter granules had reached the size of rice grains and washing 
twice with water at a temperature of 35° to 45 °F. 

Molds of various sorts quite often appear in storage butter, appar- 
ently from an infection of tubs which have previously been used for 
storing butter. The development of molds in such cases may be 
largely prevented by scrubbing and rinsing the tubs with water con- 
taining soda or common salt, or steaming the tubs for five to ten min- 
utes. The development of molds may also be largely checked by rub- 
bing the inside of the tubs with salt immediately before the butter 
is packed. Still better results are claimed from a procedure recom- 
mended by Rogers. This method consists in applying paraffine in 
a thin coat so as to> fill all the cracks in the wood of the tubs. The 
method entirely prevents the development of molds, gives a neater 
appearance to the tubs and reduces the loss from shrinkage. 

Much time and attention has been given to the study of rancid 
butter. According to Amthor rancid butter contains some alcohol 
and an intensive development of a "bouquet" takes place which soon 
renders the butter unfit for use although its wholesomeness is not affect- 
ed. Jensen in a study of the rancidity of butter found that two kinds of 
decomposition may occur in butter fat. An oxidation process may 
take place during which the unsaturated fatty acids and glycerids are 
attacked, causing a decrease in the iodin absorption number. Fats 
may also be decomposed by a hydrolytic process during which they are 
split up into glycerine and free fatty acids. Jensen maintains that 
the air plays a direct part in spoiling butter when butter is exposed 
to a high temperature. The main cause of the rancidity of butter is 
found in the action of a number of molds and bacteria which cause 
the splitting up of the fatty acids. Reinmann maintains that the 
amount of free acid in butter bears no relation to the rancid taste 
but that a high content of casein and milk sugar is favorable to the 
development of rancidity. 

In Russia, Lidow found that butter subject for long periods to the 
influence of artificial light changed in color from yellow to white and 
developed the color and flavor of tallow. The complaints which have 
been made at times regarding the flavor of canned butter have led to 
a number of investigations of this subject. Rogers found that the 
gradual loss of flavor in canned butter is due to the liberation of free 
acid which in turn is caused chiefly if not wholly by the action of a 
ferment secreted in the udder of the cow. This peculiar ferment 
appears not to be secreted except by a small percentage of cows. 

Farrington and others have studied the appearance of white spots 
on butter. This phenomenon was due to the formation of white 



302 

crystals quite unlike the mottling of butter and appearing particularly 
(in prints or bricks of butter in a refrigerator. As a rule this appear- 
ance is due to maintaining butter at low temperatures in an atmo- 
sphere so dry that the water of the brine evaporates leaving salt 
crystals on the surface of the butter. An examination of boiled or 
process butter in Philadelphia indicates that it possesses more than 
80% of fat and therefore from the standpoint of chemical analysis 
cannot be considered as adulterated. It is commonly made from 
rancid or low grade butter by reducing the butter to its original oil, 
treating it with alkali, freeing it from volatile oils and rechurning it 
with sour milk. 

Occasionally samples of butter are found with a pronounced putrid 
odor. An investigation was made of a case of this sort in Iowa by 
Eckles. The putrid butter was found to contain an abnormal number 
of bacteria which liquefy gelatine. The odor and disagreeable flavor 
arc therefore probably due to the decomposition of the albuminous 
material in the milk and butter. Occasionally a fishy flavor has 
been noted, in butter as the result of the development of Oidiun lactis. 
This trouble is readily controlled by pasteurizing the milk. 

Cheese. — As should be apparent from a consideration of the bacteri- 
ology of milk, the harmful bacteria and, their products in cheese are 
largely if not entirely due to the original contamination of the milk. 
JVI any studies have been made to determine the extent to which cheese 
may be injuriously affected by the presence of these organisms. Burri 
found that Emmenthaler cheese may be greatly injured by the de- 
velopment of a slime-producing bacillus which is sometimes secreted 
with the milk directly from the udder. In general lactic acid bacteria 
arc the most abundant organisms in cheese while the gas producing 
bacteria are relatively infrequent. The micro-organisms of different 
kinds of cheese vary largely. In the manufacture of certain cheeses, 
specific molds are used to obtain the required flavor and appearance. 
These molds are of course not of a harmful nature. Thus for example 
we have the Camembert mold and the Roquefort mold used in the 
manufacture of the cheeses known by these names. Other species 
of molds are also concerned in the production of flavors and, odors in 
cheese. The persistence of tubercle bacilli in an active condition in 
cheese is a matter which has been studied by Harrison and various 
other investigators. It appears that tubercle bacilli may remain 
virulent in Emmenthaler cheese for a period of 62 to 70 days, al- 
though their virulence was greatly diminished during the last 20 days 
of the period. In Cheddar cheese bacteria have been found to live 
for 104 days, but not with sufficient virulence to cause infection, espe- 
cially when taken into the alimentary tract. Since Cheddar cheese 
is seldom eaten under four months from the time of its manufacture 
it is apparent that the tubercle bacilli are almost certain to become 
quite innocuous before this period or ripening has been completed. 
Tubercle bacilli have been found in cottage cheese in a condition of 
virulence sufficient to infect guinea pigs when inoculated into them. 



303 

Various other abnormal conditions have been noted in cheese, a 
part of them being due to bacterial organisms. As a rule, however, 
these affect the appearance, flavor or odor of the cheese rather than 
its wholesomeness. In this class of abnormal conditions in cheese 
mention may be made of so-called pinholes, gassy cheese, swelling — 
especially in Edam cheese, excessive acidity, and the development of 
rusty spots, white specks, red coloration and other color changes. Oc- 
casionally a blue color is observed in cheese and is believed to be due 
to the presence of iron in the milk. If spongy or gassy cheese is due 
to the excessive multiplication of the coli bacillus the product may be 
unwholesome as human food,. The development of molds upon the 
surface of cheese may be largely prevented by coating the cheese with 
paraffine and maintaining it in cold storage at a low temperature. 

From time to time more or less serious cases of cheese poisoning 
are reported. The cause of this poisoning has been most thoroughly 
studied by Vaughan and a review of the literature on this subject 
has been prepared by the same investigator. In cases of cheeteic 
poisoning tyrotoxicon may be isolated, as has already been mentioned 
in referring to milk poisoning. This substance occurs more fre- 
quently in cheese than in milk but has also been isolated from ice 
cream, cream puffs and other milk products. The physiological effect 
of tyrotoxicon and the symptoms of poisoning from it have already 
been mentioned in discussing milk poisoning. 

Perhaps the most elaborate; account of cheese poisoning is that 
given by Lochte, who reports that according to> some observers cheese 
poisoning occurs most frequently in November and December and 
according to others in Summer. More than 300 cases of this trouble 
was reported by Vaughan in one epidemic in America and the history 
of other cases have been given in England, Norway, Germany and 
elsewhere. In many cases of cheese poisoning it has been found 
impossible to isolate tyrotoxicon or any other substance which could 
be definitely identified as the cause of poisoning. In order to avoid 
the occurrence of poisonous cheese, Lochte recommends that only 
the milk from healthy cows should be used in the manufacture of 
cheese and that scrupulous cleanliness be observed in drawing the 
milk and in all the processes it undergoes in the operations of cheese 
manufacture. 

Condensed Milk. — Among the numerous other milk products which 
have assumed commercial importance, mention will be made in the 
following paragraphs of some of those which are best known. The 
manufacture of various forms of condensed, milk has been undertaken 
primarily for the purpose of obtaining a nutritious product containing' 
all of the nutritive constituents of milk in a form which permits 
long keeping without serious deleterious changes. Newton proposed 
a patent process for the preparation of condensed milk in England in 
1835. Other methods were announced in rapid succession until we 
now have a number of noted manufacturers of condensed milk who 



304 

have their products on the market. The method of Borden was 
finally worked out in detail in 1866. In the preparation of condensed 
milk the chief point sought in its manufacture is to work up the milk 
in as fresh condition as possible so as to complete the operation 
before any acid develops. Small quantities of acid which may be 
present in the milk become concentrated by evaporation and may lead 
to a coagulation of the casein. The prevention of this trouble has 
been attempted by the use of alkalies in cases where some acid had 
opportunity to develop in the milk. In the method of preparing 
condensed milk as proposed by Merz an apparatus is used which holds 
5,000 liters of milk and evaporation is brought about at a temperature 
of 45 to 55 degrees C. during a period of 'Wo hours. From ten to 
twelve parts of cane sugar are added to every 100 parts of milk and 
the evaporation is carried on until the volume of the resulting product 
equals one-fifth to one-fourth of the original volume of the milk. 

A method has been proposed, by Kjeldahl for estimating the amount 
of sucrose and lactose in condensed milk at the same time. Hyde 
and others have also proposed special methods for the determination 
of solids, fat, sugar and, other constituents of canned condensed milk. 
In Germany patents have been issued for the preparation of condensed 
milk by means of a centrifugal machine. The milk in a thin layer 
is brought in contact with a cold surface revolved at the right speed 
to freeze the water out of the milk and at the same time to throw out 
the condensed product. The amount of cane sugar added to condensed 
milk is often 40% of the total volume of the product. 

Condensed milk when properly prepared seldom undergoes any 
harmful changes. Bacteria do not thrive in the condensed product 
and even if they gain entrance to it, after the process of condensation 
is complete the heat applied during the preparation of condensed 
milk is usually sufficient to destroy any bacteria which may have 
been present in the milk. Occasionally the formation of gas has been 
noted in cans of condensed milk as the result of electrolytic de- 
composition. 

Milk poivder. — A whole milk powder offered on the market in Aus- 
tria showed the presence of 20% milk sugar, 28% cane sugar, 
22% fat and 17% nitrogenous substances. The tubercle bacilli in 
milk are destroyed in the manufacture of milk powder by most of 
the processes which are in commercial operation. The same is true 
for other bacteria in milk. Apparently a milk powder in which the 
proteids exist, in their natural condition has not yet been put on the 
market, and this is considered an essential requisite of a perfect milk 
powder. Probably a whole milk powder answering this requirement 
is a difficult product to prepare, even if the danger of the powder be- 
coming rancid is obviated. The preparation of a skim milk powder 
answering all sanitary and culinary requirements is an easier matter. 
Milk powders have been prepared in Germany by evaporating milk 



305 

at a low temperature without the addition of any foreign material and 
the product is said to keep well. 

By evaporation of whole or skim milk in a vacuum at a low tem- 
perature Ekenberg succeeded in preparing a fine white powder which 
dissolves into a milk-like solution with water at a temperature of 
from 60 to 70 degrees C. This powder has the flavor of milk and 
when in solution resembles milk in most respects. The keeping 
quality of the powder is good. It does not mold, ferment, turn acid or 
rancid and is not hygroscopic. The expense of manufacturing milk 
powder by this process is about one-third of a cent per liter of milk. 
One kilogram of the powder will make ten liters of milk of normal 
concentration. The same apparatus can be used in the evaporation of 
skim milk and whey. The analysis of milk flour prepared by the 
method just mentioned shows 36% of nitrogenous matter and 49% 
of carbohydrates. In Sweden, various milk flours are prepared from 
both whole and skim milk and, the products are readily soluble in 
water. Similar processes are in common use in France and other 
countries. It is claimed for milk powders that they are not only 
readily soluble in water but that they mix with other materials used 
in preparing various food products more readily than does whole 
milk in its original state. 

Plasmon. — A product known as plasmon or caseon is prepared 
by drying the casein of milk after the fat has been removed. It is 
ordinarily a tasteless, odorless, white powder, is readily digested and 
produces no harmful effects. In the manufacture of plasmon the 
fat is removed from the milk the remainder of the milk being coagu- 
lated, kneaded, and dried at a temperature of 70 degrees C, after 
which it is ground into a powder. 

Miscellaneous milk products. — A number of evaporated milk pro- 
ducts have been manufactured on a commercial scale for a consider- 
able period. ISTutrose is essentially a combination of casein and 
sodium in a dry form. Sanose consists of 80% dried casein and 20% 
of egg albumen. In addition to these desiccated products mention 
may be made of lactone, which is an unfermented fat-free milk, 
sterilized and carbonated, Zoolak or Matzoon is a milk preparation 
in which an intense lactic acid fermentation has been brought about 
by a special ferment. 

One of the most familiar examples of milk products in which an 
alcoholic fermentation has taken place is koumiss, which is prepared 
from the milk of mares, camels or cows. In the Orient mares milk 
is chiefly used in the preparation of koumiss. Lately this product 
has been made from skim milk with lactose or cane sugar added. 
Koumiss ordinarily contains 87% water, 1.5% alcohol, 3.7% sugar, 
1% fat and .9% free carbonic acid and other constituents. 

Kephir is an alcoholic fermentation product of milk containing, 
besides alcohol, lactic acid, modified milk albumens and peptones. 



306 

The so-called kephir grain which is added for the purpose of fer- 
menting the milk consists of a cheese fungus, lactic acid bacteria and 
Dispora caucasia. All of these special milk products have been much 
advertised as beneficial in the treatment of certain diseases and when 
properly prepared seldom contain any injurious substances. In addi- 
tion to the special milk products already described mention may be 
made of junket, bonny clabber, pap, boiled milk, milk jelly, milk 
soup, peptonized milk, milk gruel, etc. 

Buttermilk. — Mention has already been made of the standard com- 
monly adopted for buttermilk. This product contains all of the con- 
stituents of milk. The fat is naturally present only to a small extent 
and the milk sugar has been largely changed into lactic acid which 
produces an agreeable flavor in buttermilk. The product should be 
consumed fresh as it is very susceptible to decomposition. In the 
case of persons in whom the digestion of fats and peptones is incom- 
plete, buttermilk furnishes an agreeable article of diet. The lactic 
acid and other bacteria which may be present in it, however, are 
likely to cause colic or diarrhoea in children. As already stated an 
artificial buttermilk is in great demand, especially throughout the 
Southern States. There is so much call for buttermilk that the market 
cannot be supplied with true buttermilk and resort has therefore 
been had to the use of skim milk about to sour, which is churned for 
a few minutes. If some evidence of butter granules is demanded by 
the customer, Doane states that a small quantity of cream is churned 
until fine butter granules are obtained, after which this material is 
added to the sour skim milk. There seems to be no objection to this 
treatment if care is used in the handling of milk. According to anal- 
yses of various samples of buttermilk the fat content ranges from 
J.% to A°/o and the total solids from 5 % to 9%. 

Ice cream,. — This product is commonly defined as a confection of 
frozen cream or custard: variously flavored. Fruit juices, sliced 
pieces of fruit or artificial flavoring extracts are extensively used in 
the manufacture of ice cream. One of the commonest forms of adul- 
teration of ice cream is accomplished by the addition of fillers of 
which the most important are cereal milling products finely ground, 
and gelatine. The fillers are added for the purpose of preventing the 
ice cream from melting too rapidly. Numerous cares of ice cream 
poisoning are reported from year to year and in most instances this 
trouble seems to be due to the presence of tyrotoxicon or some other 
ptomaine in the ice cream. The poisonous product may have beeen 
present in the milk from which the cream was obtained or may have 
developed later during the various processes in the preparation of the 
final product, 

Leben. — This product is prepared by souring and coagulating by 
means of a specific ferment the milk of buffalo, cow or goat. Leben 
is used in Egypt, Algeria and elsewhere. 



307 

Yauert or yoghurt is a name applied to milk evaporated by a low 
degree of heat to 2-3 of its previous volume, and then treated in the 
following manner : By addition of a small quantity of milk obtained 
on the previous day the casein of the partly evaporated, milk is coagu- 
lated in minute particles with the development of a small quantity 
of alcohol and carbon dioxide. The product is used in Turkey, Bul- 
garia, Paris and elsewhere. Eecently Metchnikoff has recommended 
it as very healthful on the ground that it tends to destroy or check 
the development of harmful bacteria in the intestines. Some tests 
have shown this to be the case, while in others the bacterial flora 
of the intestines was not affected, by the use of yoghurt. 

Carbonated milk. — Experiments carried on by Van Slyke and Bos- 
worth in carbonating milk have led to the following results. 

"Milk carbonated under a pressure of 70 pounds comes from the bottle 
as a foamy mass, more or less like kumiss that is two or three days old. It 
has a slightly acid, pleasant flavor, due to the carbon dioxid, and tastes some- 
what more saline than ordinary milk. In the case of carbonated milk pas- 
teurized at 185 °F., there is, of course, something of a "cooked" taste. Though 
the cream separates in the bottle, it is thoroughly remixed by a little shaking 
as the milk comes from the bottle and there is no appearance of separate 
^articles of cream. All who have had occasion to test the quality of car- 
bonated milk as a beverage agree in regarding it as a pleasant drink. In 
the case of milk bottled under a pressure of 150 pounds of carbon dioxide, 
the milk delivered from the siphon is about the consistency of whipped cream, 
but, on standing a short time, it changes to a readily drinkable condition. 
From the exDerience we have had, it would seem that, carbonated milk might 
easily be made a fairly popular beverage. 

An important question in connection with the use of carbonated milk is 
the effect of carbon dioxide gas on organisms other than lactic. While lactic 
organisms may be retarded in development, might not disease germs present 
in milk develop and thus make unsterilized or unpasteurized carbonated 
milk a possible source of danger to health? We have done no work on this 
point up to the present time, and can only refer to the meager literature on 
the subject. It should be stated that in all of our work we did not detect 
any indications of bacterial action so far as could be judged by changes 
in the flavor of the milk. Foa investigated the action of carbon dioxide gas 
under pressure of two to five atmospheres upon various organisms and 
states that it has a checking influence on the development of organisms but 
does not act on enzymes or toxines. Thus, carbon dioxide under a pressure 
of four atmospheres checks alcoholic fermentation. Hoffman treated fresb 
milk with carbon dioxide under a pressure of 50 atmospheres for some hours. 
Bacteria present in the milk were capable of growth afterwards when the 
milk wa.s relieved from pressure. This line of work needs thorough investi- 
gation and we hope to give attention to it in the near future. 

The pressure of gas employed were 70, 150 and 175 pounds per square 
inch. 

The most effective method of treating the milk was to charge it with 
carbon dioxide gas at the desired pressure in a tank such as is used in 
bottling establishments in preparing carbonated drinks and then to fill into 
bottles. 

The carbonated milk was kept at temperatures varying from 35° to 70°F. 

Pasteurized milk, carbonated, kept for five months with little increase in 
acidity. Fresh, whole milk, carbonated, kept, in one experiment, for about 
the same length of time. 

Carbonated milk makes a pleasant beverage and may find practical use 
as a healthful drink. It may also be found useful for invalids and children." 



308 



CHAPTER XVI. 

HISTORY OF MILK INSPECTION. 

Since the dawn of history milk has constituted one of the staple 
articles of diet of all human races. From the numerous references 
made to milk in poetical, scientific and historical literature of ancient 
times it is apparent that this food product in a fresh form, or as 
butter, cheese and various other special products has always been of 
great importance in the nutrition of man. 

In India the chief milk-giving animals are the zebu and buffalo. 
From these animals milk was obtained, and consumed as such or man- 
ufactured into butter and ghee as early as 1500 B. C. According 
to various Jewish writers it is apparent that the Hebrews consumed 
large quantities of milk from cows, sheep and goats and were fairly 
well acquainted with the manufacture of butter, although this word 
has probably been used incorrectly in some of the translations of 
Hebrew literature. According to Burckhardt the Arabs eat unusually 
large quantities of butter as an independent article of diet and also 
use it to an excessive extent on other food products. 

Brief references are found regarding the existence of a dairy in- 
dustry in Egypt as early as 2000 B. C. Apparently the milk used by 
the Egyptians was largely from goats and sheep. The Greeks like- 
wise in the time of Homer consumed large quantities of sheep and 
goat milk as well as the milk from mares and asses. Butter was 
quite extensively used by the Greeks and a cheese was prepared by 
the use of fig sap and rennet. Aristotle and various other Greek 
writers refer to the relative composition of the milk of camels, mares, 
asses and other animals. It was a matter of common knowledge 
among the Greeks that the flavor and wholesomeness of milk were 
considerably influenced by the feed stuffs consumed by the cows. 
Vetches were considered as particularly favorable to the production 
of large quantities of high grade milk. Strangely enough complaints 
w 7 ere made of the unfavorable effect of alfalfa upon milk. 

The Romans devised a number of methods for the production of 
a sour milk product commonly referred to as oxygala. This was pre- 
pared by a special process of fermenting sheep's milk. The peculiar 
constitution of colostrum was also understood by various Roman 
writers who referred to it as having an unusual density and as showing 
a spongy nature. 

The early literature of the English and other peoples of Northern 
and Central Europe abounds in references to the use and importance 
of milk and milk products. In England the county of Cheshire was 



309 

famous for its cheese as early as the beginning of the 12th century. 
Similarly Switzerland became noted for her dairy products in the 
13th century and the Holstein region of Holland at about the same 
period. 

During the middle ages a body of superstitious beliefs gradually 
grew up around the subject of milk and its properties. Various 
mysterious factors were believed to be concerned in the successful 
production of butter and cheese and the souring of milk and develop- 
ment of abnormal conditions in it were attributed to witchcraft and 
other mysterious forces. These superstitious beliefs gradually faded 
away under the influence of scientific investigation but persisted among 
a considerable proportion of the common people until within recent 
years. In fact the supposed influence of thunder storms in the souring 
of milk may be instanced as an example of such a belief which has 
persisted until the present day. 

In the 17 th century milk sugar was definitely isolated and the fat 
globules of milk were discovered soon afterward. Notable contribu- 
tions to the composition and properties of milk were made by Gesner 
in 1549 and Webersky during the same century. In a number of 
publications in England during the middle of the 18th century spe- 
cific mention is made of the injurious effect of certain feeds, particu- 
larly turnips and cabbage upon the flavor of milk and also of the 
transmission of drugs and metallic substances from the cow to the 
milk. The causes of the fermentation of milk were investigated to 
some extent at the same time and lactic acid was isolated. In the 
beginning of the 19th century an important contribution was made 
to the knowledge of milk by Parmentier and Deyeux, who carefully 
studied the composition and behavior of milk sugar in comparison 
with cane sugar. Some attention was also given to the specific gravity, 
freezing point and other physical characteristics of milk. 

In all civilized countries a knowledge of the composition and biologi- 
cal characteristics of milk and of the factors which influence its keep- 
ing qualities and wholesomeness have preceded by a considerable 
period the enactment of definite laws controlling the milk supply. It 
is only natural that this should have been the case since definite facts 
regarding the possible contamination and unwholesomeness of milk 
must first have been worked out before any demand would have arisen 
for the supervision of the milk supply. In general the demand for 
the regulation of the milk supply has arisen first in large cities in 
which, as their size increased, the difficulties of furnishing wholesome 
milk according to the old methods became greater and greater. The 
first point concerning which laws were demanded was the matter of 
adulteration of milk and in many of the early laws this was the only 
point mentioned. If we may believe that the early milk inspection 
laws reflected the conditions which prevailed in the milk business, 
the extent of dilution of milk with water became at some time or 
other an exceedingly serious matter in nearly all large cities. 



310 

In England the first milk law was passed in 1860, and had to do 
only with the adulteration of milk. The law prohibited the dilution 
of milk with water or the use of other substances for the purpose of 
concealing dilution. The first attempt in England to regulate- in a 
general way the city milk supply was put on foot in 1806 under the 
direction of the Aylesbury Dairy Company, an example of numerous 
other similar institutions which have developed as necessary growths 
in sanitary regulation of municipal milk supplies. Before such 
companies were established the milk supply of all large cities came 
from a large number of milk dealers and dairymen who owned a few 
cows kept under greatly varying conditions. The quality of the milk 
therefore varied greatly at different seasons and striking differences 
were noted in the composition and wholesomeness of the milk of 
different dealers. The establishment of large dairy companies, often 
of a co-operative nature, was therefore recognized as an absolute ne- 
cessity in securing a tolerably uniform quality for the milk supplied 
to any given city. At the beginning of the existence of the Aylesbury 
Dairy Company, two grades of milk were established, one of which 
was considered suitable for immediate consumption in the fresh state, 
while the other was held to be unsuitable for such use and was churned 
for the production of butter. The plan adopted by the Aylesbury 
Dairy Company was based on that of a similar company known as 
the Willowbank Dairy, which was started in Glasgow in 1809. 

As already indicated similar sanitary commercial institutions for 
the control of a milk supply were established, in various other countries 
at about the same time with the Aylesbury Dairy Company in Eng- 
land. Thus in Hamburg the Farmers' Co-operative Dairy Company 
was established in 1863, a similar one in Liibeck in 1879, in Berlin 
and Vienna in 1891 and in various parts of Denmark and other 
Scandinavian countries in 1881 and 1884. The purpose of the present 
union of Berlin milk dealers is essentially the same as that of the 
companies already mentioned. The Central Co-operative Creamery 
Society of Budapest began its existence in 1883 on a small scale and 
now covers two acres of ground and handles about 9,000 gallons of 
milk daily. The results which this society seeks to accomplish are 
the supply of the best possible milk to consumers and the maximum 
profit from the milk to farmers. So-called control unions have been 
established among dairymen very extensively in most parts of Europe. 
Of these unions there are 204 in Sweden, 120 in Norway, 40 in Fin- 
land, 3 in Holland, 2 in Scotland and 5 in Austria. The purpose of 
the control unions is to promulgate by co-operative efforts among 
dairymen information and improved, methods regarding the feeding 
and care of dairy cows and the care and handling of milk in order 
to produce a large supply of pure milk at a reasonable profit for the 
dairyman. A great amount of good has been accomplished by the 
control unions along this line. 

In all of the English colonies some legislative attention has been 



311 

given to the control of the milk supply. Milk inspection is not every- 
where put. on an independent basis and therefore the results are not 
always as satisfactory as could be desired. In New Zealand, stock 
inspectors have also the duty of taking -samples of milk for analysis 
and examination by chemical and bacteriological experts and also of 
inspecting dairy cows and premises. 

In Germany the only general imperial law relating to milk inspec- 
tion and holding good, for the whole empire is that of 1879 on foods, 
condiments and manufactured articles. This law forbids the adultera- 
tion or use of harmful preservatives in all kinds of food products and 
has naturally been held to apply to milk. Complaints have occasion- 
ally been made by veterinary and sanitary authorities in Germany 
that further general legislation on the subject of milk inspection is 
necessary. Other authorities, on the contrary, have held that the 
milk supply of cities cannot be regulated by an imperial law in greater 
detail than is now accomplished by the law on foods and condiments. 
The conditions vary so much in different localities, that each city 
must apparently regulate the matter independently. An imperial 
com, mission however has a general supervision of local regulations of 
milk inspection in German municipalities. In Berlin the specific 
gravity of the milk is determined and the fat percentage by a chem- 
ical analysis. Milk of diseased cows, especially those affected with 
foot and mouth disease, is not admitted for human consumption. In 
Bromberg, lactometer tests are made by police officials. Market milk 
is required to contain 12.25% of total solids. Tests are also made for 
the percentage of fat and for possible adulteration. In Bromberg as 
well as in all other cities of Germany the milk of cows suffering from 
contagious mammitis, enteritis and septic metritis is excluded from 
the market. 

According to a ministerial circular decree of 1899 with modifica- 
tions announced in 1900, the traffic in fresh, boiled, sterilized or 
sour milk and buttermilk in Prussia is under police supervision. 
Milk may be offered on the market in the form of whole milk, half 
milk, skim milk and buttermilk, each quality of milk being properly 
labelled. Whole milk must show 2.7% of fat, half milk 1.5% of fat 
and, skim milk .15% of fat. The specific gravity of whole milk may 
vary between 1,028 and 1,034, half milk between^ 1,030 and 1,036 and 
skim milk between 1,032 and 1,037. The minimum, permissible fat 
content of cream is 10%. Boiled milk is understood as having been 
brought to a temperature of 100 degrees C. or maintained at a tem- 
perature of 90 degrees C. for 15 minutes. 

The circular decree prohibits the admission to the market of milk 
obtained just before calving or within six days after calving; the 
milk of cows affected with anthrax, black leg, rabies, cow pox, jaundice, 
dysentery, blood poisoning and inflammations of the udder; the milk 
of cows which are being treated with various drugs, such as arsenic, 
opium, eserin, etc. ; the milk of cows affected with mammary tubercu- 



312 

losis; all milk which contains foreign bodies including ice and 
chemical preservatives; all blue, red or yellow milk and milk con- 
taminated with molds or blood, clots or showing changes due to 
bacterial action. The milk of cows which 'are affected with foot and 
mouth disease or tuberculosis cannot be used until after sterilization. 

The circular decree in question specifies in detail a set of rigid 
conditions under which milk, for children must be produced. 

In Copenhagen, The Milk Society Trifolium has assumed a gem 
eral supervision of part of the city supply of milk. A physician and 
a veterinarian constitute a committee for the decision of points of 
sanitation which may arise in connection with the milk supply. The 
Trifolium Milk Society is under obligation to this committee to 
furnish milk which contains at least 3% of fat. Milk intended es- 
pecially for children must be produced on premises on which approved 
sanitary methods are in vogue and from cows free from tuberculosis 
and other dangerous diseases and repeatedly tested with tuberculin. 
The society agrees to furnish veterinarians who shall work under 
the direction of the control committees consisting, as already stated, 
of one physician and one veterinarian. On the premises from which 
milk is obtained it is necessary that a veterinary inspection be made 
from time to time and that all diseased animals be isolated and their 
milk excluded from the general supply coming from the herd. Cows 
purchased by dairymen from outside sources must be inspected by 
a veterinarian under the supervision of the control committee before 
the milk is allowed to be mixed with that of the herd. Detailed 
specifications are also furnished regarding the required health of 
milkers, the feeding stuffs given to the cows, particularly turnips, 
distillery refuse, brewers' grains and other feeds which may affect 
the quality or flavor of the milk and regarding the methods of milking 
and handling the milk until it reaches the consumer. 

In Italy the dairymen are required to give notice of their intention 
to open a dairy and to furnish milk for city use. The premises and 
cows are then inspected and also all details about the premises, even 
the bedding and milk room. The latter must be as far as possible 
from the stable. The dairymen are required to give immediate notice 
of sickness in any of the cows and the milk from such cows cannot 
be offered for sale until a veterinarian pronounces it wholesome. Only 
suitable and wholesome feeding stuffs are permitted to be used. The 
Italian milk regulations forbid the sale of milk from diseased cows 
or from cows improperly fed, as well as adulterated milk or milk 
showing any of the common abnormalities. 

In Paris a strict veterinary inspection is made of dairies for the 
purpose of excluding from the market milk from cases of mammitis 
and other dangerous diseases in cattle. Veterinary inspectors also 
have the duty of examining and, passing upon the general sanitary 
conditions of the premises. A permanent commission for the preven- 
tion of tuberculosis takes cognizance of all tuberculous cows and issues 



313 

instructions regarding the disposal which shall be made of these 
cows and their milk. 

Essentially the same stages have been passed through in the develop- 
ment of the dairy industry in this country as have been noted in 
Europe. With the concentration of large masses of population in 
the chief cities of the country the problem of furnishing an adequate 
milk supply of a wholesome nature became more and more compli- 
cated. The difficulties connected with this situation were appreciated 
by both the producers and consumers but as has happened in the 
manufacture and sale of nearly all other food products much diffi- 
culty was experienced in securing an effective co-operation between 
the producer and the consumer to the end that better milk might be 
supplied. The first complaints which were heard f roan the consumers 
regarding the quality of milk related largely to adulteration, especially 
with water, the use of preservatives and the presence of unnecessary 
quantities of filth. Naturally, therefore, the first laws passed for the 
control of the municipal milk .supplies contained chiefly clauses pro- 
hibiting the adulteration of milk and compelling the observance of 
more sanitary methods by the dairymen. In many instances these 
laws were quite ineffective for the reason that no provision was made 
for the appointment of milk inspectors. Where no inspectors were 
provided for, the consumer had no recourse except to complain to offi- 
cials who had to deal with other sorts of nuisances and to attempt to 
get redress in that manner. 

So far as we have been able to determine, the first law for the con- 
trol of the milk supply was passed in Boston in 1856. This law mere- 
ly prohibited the adulteration of milk. A new law passed by the 
Massachusetts Legislature in 1859 provided for inspectors and the 
office of the Boston Milk Inspector was established on August 10. 
1859. The law under which this office was established was again re- 
vised in 1864 and clauses were added forbidding the use of distillery 
refuse as feed for dairy cows and also forbidding the use of milk from 
diseased cows. 

There has been a legal foundation in New York for the analysis of 
milk and testing for fat since 1869. In 1870 the inspectors' reports 
in New York City indicated that the average market milk contained 
one quart of water to each three quarts of milk. At that time, there- 
fore, the inspectors were largely occupied in detecting adulterations. 

At the present time an unusual amount of attention is paid to the 
sanitary condition of the milk supply of Boston. The State Board 
of Health of Massachusetts makes a veterinary inspection of dairies 
which supply the city with milk. The veterinary inspection of the 
dairies takes account of the condition of the cow stables, their con- 
struction, means of ventilation, nature of floor and stalls, quality of 
bedding, disposal of manure, location and storage of feeding stuffs, 
general conditions as to cleanliness, source of water supply, distance 



314 

of water supply from the stable, direction of the ground level from 
the source of water supply, condition of cows' udders, temperature of 
the milk, washing of dairy utensils, use of ice, length of the haul of 
the milk to the station and condition of the milk at the time of de- 
livery at the station. In addition to the veterinary inspection of the 
cows and dairy premises, the milk is subjected to chemical and bacte- 
riological tests after it has arrived in Boston. The bacteriological 
standard adopted allows a maximum of 500,000 bacteria per c.c. 

The milk supply of New York varies considerably in its quality but 
the recent continued campaign for pure milk in that city has led to a 
great improvement in the average quality of the milk delivered at the 
metropolis. A considerable amount of pressure has been brought to 
bear upon dairymen by the milk dealers of the city who are supported 
by an association of physicians in testing the milk and inspecting the 
dairy premises. As stated by Whitaker and others milk produced 
from healthy cattle under approved sanitary conditions is certified by 
an association of physicians, and since certified milk commands an 
extra price an increasing number of dairymen have improved their 
premises and methods so that they may produce such milk. In some 
instances where the milk is carefully drawn, immediately cooled at 
38 degrees F. and handled under sanitary conditions it reaches the 
market with a bacterial content between 1,500 and 5,000 per c.c. 

In Philadelphia, the Philadelphia Pediatric Society is especially in- 
terested in securing a supply of pure milk for children. This society 
appointed a committee in 1898 to investigate the problem of improv- 
ing the municipal milk supply. An examination of the dairy premises 
and the milk furnished by dairymen was made once per month. Milk 
intended for children must come from healthy cows in well cleaned 
and ventilated stables, must show a neutral or faintly acid reaction, 
not less than 3.5% of fat, and must be free from all foreign matter and 
chemical preservatives. It is also required that the milk shall not 
contain pus nor pathogenic bacteria nor more than 10,000 bacteria of 
any kind per c.c. 

The milk inspection division of the Department of Health in Chi- 
cago was established in 1892. A license was required for all dairy- 
men, and chemical standards were established for market milk. An 
inspection of the milk supply for Chicago has become more and more 
strict and efficient in recent years, partly as the result of the occur- 
rence of serious epidemics of scarlet fever and diphtheria which were 
traced apparently to the milk supply. 

The necessity for a general campaign for pure milk has become more 
and more apparent throughout the country during recent years and 
has led to the enactment of legislation in all of the States and Terri- 
tories and to the establishment of municipal ordinances regarding 
milk in nearly all of the cities throughout the country. 

In some instances these laws are highly defective and fail to provide 



315 

the proper officials for their enforcement or fail to require a sufficiently 
rigid inspection of the milk. It is obviously an inadequate protection 
of the public merely to examine samples of milk which may be offered 
upon the market for the purpose of determining the chemical com- 
position and. bacteriological content of these samples. It has repeated- 
ly been shown that where both temperature and bacterial standards are 
set up for milk it is necessary to make use of both of them in order to 
reach any just conclusion regarding the quality of the milk. Thus 
it may well happen and often does happen that adequate refrigeration 
is not applied to milk during its delivery to the market but that despite 
the absence of refrigeration the milk reaches the market relatively free 
from bacteria. This indicates that the milk was drawn and handled 
with special care and under satisfactory conditions. On the other 
hand numerous samples of market milk are found in which the tem- 
perature is below 50 degrees F. but in which the bacterial contamina- 
tion is enormously high. This in turn indicates that filthy habits or 
carelessness have contributed to the contamination of the milk and that 
the use of ice has not been sufficient to obscure this contamination. 

It has come to be recognized that a proper system of milk inspec- 
tion should include the registration of all dairies furnishing milk to a 
given city, the veterinary inspection of cows, barns, milk rooms and 
other features of the dairy premises at least once a month, the eradica- 
tion of tuberculosis from dairy herds, the branding of condemned cows 
so that they may be readily identified, the requirement of wholesome 
feeding stuffs for all dairy cows, the careful and thorough cleansing of 
all milk utensils, the immediate application of refrigeration to milk as 
soon as it is drawn, chemical and bacteriological examinations of milk 
at the city terminus, severe penalties for the violation of milk laws 
and public reports on the conditions observed at each dairy and on 
the bacterial count determined in samples of milk. 

As a result of the agitation which has long been going on in the Dis- 
trict of Columbia for the improvement of the milk supply, a commis- 
sion has been appointed which, it is believed, receiving as it does the 
active support of the President, the Board of Health, the Department 
of Agriculture and other bacteriological experts, will put into opera- 
tion one of the most efficient systems of milk inspection which has yet 
been devised. This system as at present outlined rests upon the solid 
foundation that an efficient milk inspection must begin at the farm 
where the milk is produced and must follow the milk through all of 
the processes of handling until it reaches the consumer. 



316 



CHAPTER XVII. 

BIBLIOGRAPHY OF MILK INSPECTION. 

The references which have been selected for this list include those 
books and articles consulted in the preparation of this, volume which 
are believed to be of most value to the milk inspector and dairyman. 
It is far from complete on any subject. The bibliography of milk 
inspection in a broad acceptation of the term is immense, and has al- 
ready been made accessible. Rothschild's Bibliographia lactaria and 
the supplements published to date include nearly 11,000 titles of arti- 
cles. Perhaps the best selected bibliography of the sanitary aspect of 
milk is to be found in "Milk and its relation to the wealth and health 
of the people" published in Hamburg in 1903. A large bibliography 
is also given in Snyder's Dairy Chemistry. The following references 
have been arranged according to the chapters to which they naturally 
belong, but many books and articles, as indicated by their titles, cover 
several chapters. 

Chapter I. Normal, Milk. 

Aikman, C. M 

Milk, its nature and composition. London 1899, pages 180. 
Belcher, S. D. 

Clean Milk. New York 1903 page 146. 
Brainerd, 

Clean and sanitary milk. Vir. Bui. 185. 
Bertkau, P. 

Anatomy and physiology of the udder. Anat. Anz. 1907, page 161. 
Pleischmann, W. 

Specific heat of milk. Jour, fur Landwirtsch. 1902, page 33. 

Lehrbuch der Milchwirtschaft. Leipsic, 1901. 
Fiirstenberg, M. H. F. 

Die Milchdriisen der Kuh. Leipsic 1868, pages 215. 

Hewlett, 

The cellular elements in milk. Jour. Hyg. (Cambridge) 1910 
pages 56-92. 
Hougardy, A. 

Kinase in milk. Acad. Roy. Belg. Bui. CI. Sci. 1906 pages 
888-900. 



317 

Jordan, W. H. et al. 

Source of milk fat. 1ST. Y. State Exper. Station Buls. 132 and 
197. 
Kirchner, W. 

Handbuch der Milchwirtschaft etc. Berlin, 1898 pages 654. 
Klein, J. 

Erfolgreiche Milchwirtschaft. Berlin 1902. 
Kriiger. 

Knhkolostrum. Mlolkereizeitung, 1892, page 16. 

Leze. 

Les globules du lait. Jour. Agric. prat. 1900, page 152. 

Lindet, L. 

Le lait, la creme, le beurre, les fromages. Paris, 1907, pages 347. 
Maercker, M. 

Futterungslehre. Berlin, 1902. 

Martiny, B. 

Die Milch, ihr wesen und ihre Verwerthung. Danzig. Vol. I 
1871 pages 438. Vol II 1872 pages 368. 

Otto, A. 

Die Milch und ihre Producte. Berlin, 1892 pages 182. 
Partsch, C. 

Uber den feineren Ban der Milchdruse. Inaug. Diss. 1880. 
Pearson, R. A. 

Facts about milk. Farmers' Bulletin 42. 
Portanier. 

Le lait. Mce 1900. 
Richmond, H. D. 

The composition of milk. Analyst 32 (1907) pages 141-144. 
Rothschild, H. de. 

Bibliographia lactaria. Paris 1901 and supplements. 
Sommerfeld. 

Haudbuch der Milchkunde. 1909 pp. 999. 
Stieger, W. 

Die Hygiene der milch. Leipsic. 1902 pages 244. 
Stolmann, F. 

Die MKlch und Molkereiproduete. 1898 pages 1031. 
Stone and Sprague. 

Leucocytes in milk. Jour. Med. Research 1909 pp. 235, 243. 

Thierfelder. 

Entstehung einiger Milchbestandtheile. Inaug. Diss. Rostock. 
1883. 
Thomson. 

The dairying industry. London 1907 pp. 263. 



318 

Thompson, G. F. 

Information concerning milch goals. Bur. Anim. Ind. Bui. 68. 

Ward and Jaffa. 

Pure milk and the public health. 1909 pp. 218. 
Wassemann. 

Eiweissstoffe verschiedener Milcharten. Munch. Med. Wochensch. 
1900 page 986. 

Willoughby, E. F. 

Milk, its production and uses etc. London, 1903 pages 259. 

Wing, H. H. 

Milk and its products. New York, 1897 pages 230. 

Wing, H. HI. 

Effect of feeding fat to cows. K Y. Corn. Exper. Station Bui. 92. 

Wing, H. H. and L, Anderson. 

Studies in milk secretion N. Y. Corn. Exper. Station Buls. 152 
and 169. 
Die Milch und ihre Bedeutung fur Volkswirtschaft und Volksgesund- 

heit. Hamburg, 1903 pages 522. 
Milk and its relation to the public health. Hygienic Laboratory, Bui. 
41 pages 758. 1908. 

Chapter II. Abnormal Milk. 

Andra. 

Einflus der Schlempe auf die Beschaffenheit der Milch. Fiihlings 
landw. Zeit. 1887 page 177. 
Axe. 

Milk in relation to public health. The Vet, 1885- pages 308 and 
384. 

Brahm, C. 

The ferments of milk. Zentrbl. gesam. Physiol, path. Stoffwech- 
sels 1907 pages 81 and 129. 

Clark, E. W. 

Dairy herd record and creamery notes. Ala. Exper. Station 
Bui. 121. 

Doane, C. F. 

The character of milk during the period of heat, Md. Exper. 
Station Bui. 95. 

Doane, C. F. 

Leucocytes in milk and their significance. Md. Exper. Station 
Bui. 102. 

Ferris, S. 

A dissertation on milk etc, London 1785 pages 206. 
Fraser, W. J. 

Effect of silage on flavors of milk. 111. Exper. Station Bui. 101. 



319 

Harding, H. A. et al. 

Notes on some dairy troubles. N. Y. State Exper. Station Bui. 
183. 
Harnier. 

Quaedam de transitu medicamentoruin in lac. Inaug. Diss Mar- 
burg. 1847. 

Harris, K ML 

The relative importance of streptococci and leucocytes in milk. 
Jour. Infect. Diseases 1907 Sup. pages 50-63. 
Jensen, C. O. 

Grundriss der Milchkunde und Milchhygiene. Stuttgart 1903 
pages 228. 
Jensen, O. 

Oxydases and reductases in cow's milk. Bev. gen. Lait. 1906 
pages 34, 56 and 85. 
King, F. H. 

The construction of silos and the making and handling of silage. 
Wis. Exper. Station Bui. 59. 
Klingeman. 

Der Uebergang des Alkohols in die Milch. Virch. Arch. vol. 
126. 
Kober, G. M. 

Milk in relation to public health. Washington 1902 pages 235. 
Leach. 

Foreign coloring matters in milk. Jour. Amer. Chem. Soc. 1900 
page 207. 
Lindsey, J. B. 

Distillery and, brewery byproducts. Mass. Hatch Exper. Station 
Bui. 94. 

Marcas, L. and C. Huyge. 

Elimination of nitrates by the udder. Bui. Agr. (Brussels) 1906 
page 217. 
Marshall, C. E. 

Ropiness in milk. MEch. Exper. Station Bui. 140. 

Marshall, C. E. 

A popular discussion of pure milk supply. Mich. Exper. Station 

Bui. 182. 
Monvoisin, A. 

Composition of tuberculous milk. Rev. gen. Lait. 1906 pages 

457, 492. 

Parmentier and Deyeux. 

Precis de experiences et observations sur les differentes especes 
de lait. 1800. 



320 

Prescott and Breed. 

Leucocytes in milk. Sci. 1910 p. 552. 
Re vis, C. and A. Payne. 

The acid coagulation of milk. Jour. liyg. 7 (1907) pages 216- 
231. 
Eugg. H. H. 

Observations on London milk etc. London 1849 pages 82. 

Russell, H. L. 

Tainted or defective milks. Wis. Exper. Station Bui. 62. 

Russell, H. L. 

Absorption of odors by warm and cold milk. Wis. Station Re- 
port for 1898 page 104. 
Russell, H. L. and C. Hoffman. 

Leucocyte content of milk drawn from apparently healthy ani- 
mals. Jour. Amer. Med. Assoc. 1906 page 2110. 
Savage. 

Streptococci and leucocytes in milk. Jour. Liyg. 1906 page 123. 
Schaffer. 

Die Zusammensetzung der Kuhmilch mach dem Verwerfen. 
Schweizer landw. Jahrb. 1895. 
Scholl, H. 

Die Milch, ihre haufigere Zersetzungen etc. Wiesbaden 1891 
pages 137. 
Slack. 

Methods of bacteriological examination of milk. Jour. Infect. 
Diseases Sup. 2 1906 page 214. 
Smidt, H. 

So-called reductase in milk. Arch. Hyg. 1906 page 313. 

Spallangani. 

L'arsrnico nell' alimentazione. Clin. Vet. vol. 9, page 517. 
Stewart. 

Methods employed in the examination of milk by city health 
authorities. Amer. Med. vol. 9, page 486. 
Stokes. 

The microscopic examination of milk. Ann. Rept. Bd. Health 
Baltimore 1897 page 105. 
Turton, E. and R. Appleton. 

The relative opsonic power of the mother's blood serum and milk. 
Brit. Med. Jour. 1907 page 865. 
Vandevelde, A. J. J. 

Milk and, milk adulteration. Ghent 1907 pages 110. 
Vaughan, V. C. and F. G. Novy. 

Ptomains, leucomains, toxins and antitoxins. Phil. 1896 pages 
604. 



321 

Ward, A. E. 

Ropiness in milk and cream. 1ST. Y. Corn. Station Bui. 165 
and 195. 
Ward, A. R. et al. 

The numerical determination of leucocytes in milk. 19th. bien. 
Rpt. State Bd. Health Calif, pages 142-156. 

Woodhead, G. S. and W. A. Mitchell. 

Opsonins in milk. Jour. Path, and Bact, 1907 page 408. 

Woods, C. D. 

Feeding fat into milk etc. Bur. Anim. Ind. Circ 75. 

Woll, F. W. 

Soybean silage for cows. Wis. Rpt. for 1904 pages 67-74. 
Woll, F. W. 

Relation of food to production of milk and butter fat. Wis. 
Station Bui. 116. 
Wiithrich. 

Einfluss roher Kartoffeln auf die Milch. Milchzeitung 1896. 

Chapter III. Hygiene and Diseases of Cows. 

Dammann, C 

Gesundheitspflege der landwirtschaftlichen Haussaugetiere. Ber- 
lin 1902. 

Friedberger, F. and E. Froehner. 

Lehrbuch der speciellen Pathologic und Therapie der Haustiere. 
Stuttgart 1900. 

Johne, A. 

Gesundheitspflege der Haussaugetiere. Berlin 1898. 
Law, J. 

Veterinary Medicine. Ithaca, 1ST. Y., 5 volumes, 1905. 
Law, J. 

Experiments with tuberculin on non-tuberculous cows. ~N. Y. 
Corn. Station Bui. 82. 
Law, J. 

Tuberculosis in relation to animal industry and public health. 
K Y. Corn. Station Bui. 65. 
Marshall, C. E. 

Normal temperatures and the tuberculin test. Mich. Exper. Sta- 
tion Bui. 159. 
Mayo, K S. 

The care of animals. New York, 1903. 
Mbore, V. A. 

The pathology of infectious diseases. Ithaca. 1902. 



322 

Niemann, F. and 0. Profe. 

Grimdriss der Veterinarhygiene. Berlin. 1903 pages 418. 

JSTocard, E. and E. Leclainche. 

Les maladies microbiennes des animaux. Paris 1903 pages 1313. 

Pages, C. 

Hygiene des animaux domestiques dans la production dn lait. 
Paris 1896 pages 324. 

Russell, H. L, 

Tuberculosis and the tuberculin test. Wis, Exper. Station Bills. 
40, 78, 84, 114, 126, 133. 

Wilson, J. T. 

Dairy sanitation. San. Jour. 1896-1897. page 650. 

Special Report on Diseases of Cattle. Bur. Anim. Ind, 1904. 

Chapter IV. Feeding Cows. 

A.rmsby, H. P. 

Manual of cattle feeding. N. Y. 1887. pages 525. 

Dechambre, P. 

Les aliments du Betail. Paris. 1906 pages 578. 

Henry, W. A. 

Feeds and feeding. Madison, Wis, 1903. pages 657. 

Jordan, W. H. 

Feeding animals. 1ST. Y. 1901. pages 450. 

Kellner. O. 

Die Ernahrung der landwirthschaftlichen ISTutztiere. Berlin. 
1905. pages 594. 

Pott, E. 

Uandbuch der tierischen Ernahrung etc. Berlin. 1904. pages 
389. 

Smith, H. R. 

Profitable stock feeding. Lincoln, ISTeb. 1906. pages 413. 

Wilcox, E. V. 

Farm animals. N. Y. 1906. pages 357. 

Wilcox, E. V. and C. B. Smith. 

Farmer's Cyclopedia of Agriculture. 1ST. Y. 1904. pages 619. 

Wilcox, E. Y. and C. B. Smith. 

Farmer's Cyclopedia of Live Stock. N. Y. 1908. pages 745. 
Consult also the bulletins and reports of the various agricultural ex- 
periment stations, especially those in Connecticut, Illinois, Kansas, 
Massachusetts, Michigan, New Jersey, New York, Pennsylvania, Ver- 
mont and Wisconsin. 



323 

Chapter V. Buildings and Premises. 

Clark, A. D. 

Modern farm buildings. London 1899 pages 194. 

Doane, C. F. 

Tests of materials for bedding cows, Md. Exper. Station Bui. 
104. 

Engel, F. 

Der Viehstall etc. Berlin 1889 pages 194. 
Fraser, W. J. 

Should dairy cows be confined in stalls ? 111. Exper. Station 
Circ. 93. 
Halstead, B. D. 

Barn plans and outbuildings. New York, 1903 pages 388. 
Hill, G. G. 

Practical suggestions for farm buildings. Farmers' Bulletin 126. 
Hopper, H. A. 

Suggestions for improvement of dairy barns. 111. Exper. Station 
Circ. 95. 
Hunter, A. F. 

Practical farm buildings. East Walpole, Mass. 1905 pages 24. 
King, F. H. 

Elementary lessons in the physics of agriculture. Madison Wis. 
1894 pages 184. 
McLean, P. 

Suggestions for building a cool dairy. Queensland Dept. Agric. 
Bui. 11. 
Maiden, W. J. 

Farm buildings etc. London 1896 pages 192. 
Pearson, R. A. 

Market milk, a plan for its improvement. Bur. Anim. Ind. Rpt. 
for 1900 pages 158-193. 
Reynolds, M. H. and C. C. Lipp. 

Stable ventilation etc. Minn. Exper. Station Bui. 98. 
Richards, W B. and E. L. Jordan. 

Stable temperatures and milk yield,. Wis, Station Rpt. for 1904 
page 143. 
Wolpert. 

Ueber Luftwechsel, Lufterneuerung und Ventilation. Kochs Vet, 
Encyclop. vol. 6 Leipsic 1889. 
Suggestions for the construction of a modern dairy barn. Bur. Anim. 

Ind. Circ. 90. 
Ventilation of Stables. Farmers' Bulletin 190. 
Farm Buildings. Chicago 1905. pages 185. 



324 

Chapter VI. Milking and the Handling oe Milk. 

Allyn. 

Paper milk bottles. Milk Man 1910 p. 9. 

Bolley, H. L. 

Cleanliness in handling milk. N. D. Exper. Station Bui. 21. 

Clark, E. W. 

Care of milk on the farm. Utah Station Bui. 96. 

Conn, Ii. W. and W. A. Stocking Jr. 

Bacteria in strained and unstrained milk etc. Storrs Station 
Rpt. for 1902 page 33. 

Cottrell et al. 

Keeping milk in summer. Kans. Station Bui. 88. 

Doane, C. F. 

The disinfecting properties of washing powders. Md. Station 
Bui. 79. 
Doane, C. F. 

Economical methods of improving the keeping qualities of milk. 
Md. Station Bui. 88. 
Erf, O. 

Milking machines Kans. Station Bui. 140. 

Erf, O. and C. W. Melick. 

Care of dairy utensils. Kans. Station Bui. 131. 
Eraser, W. J. 

Preventing contamination of milk. 111. Station Bui. 91. 
Fraser, W. J. 

City milk supply. 111. Station Bui. 92. 

Haecker and Little. 

Milking machines. Neb. Bui. 108. 

Haecker, A. L, and C. W. Melick. 

Methods of controlling contamination of milk during milking. 
Neb. Station Bui. 87. 
Hofman-Bang. 

Milking machines. Ber. K. Vet. og Landbo. Lab. Landok. Forsog 
68 (1910). 
Hunziker, O. F. 

Care and handling of milk. Corn. Station Bui. 203. 
Harding et al. 

The modern milk pail. N. Y. State Bui. 326. 

Lane, C. B. and W. A. Stocking Jr. 

The milking machine as a factor in dairying. Bur. Anim. Ind. 
Bui. 92. 
Marshall, C. E. 

Aeration of milk. Mich. Station Bui. 201 and Spec. Bui. 16. 



325 

Marshall, C. E, et al. 

Care and handling of milk. Mich. Station Bui. 221. 
Pearson, R. A. 

Care of milk on the farm. Farmers' Bulletin 63. 
Plumb, C. S. 

Dairy experiments. Ind. Station Bui. 44. 
Seibert, A. 

The nitration of milk through absorbent cotton. K". Y. Med. 
Jour. 1895 page 214. 
Stocking, W. A. Jr. 

The covered pail as a factor in sanitary milk production. Storrs 
Station Bui. 25. 
Stocking, W. A. Jr. 

Quality of milk as affected by common dairy practices. Storrs 
Station Bui. 42. 
Vieth, P. 

Fliegels Milchfilter. Zeit, Fleisch. Milchhygiene. 1901 page 326. 
Wall and Humphrey. 

Milking machines. Wis. Bui. 173. 
Webster, E. H. 

The farm separator. Bur. Anim. Ind. Bui. 61. 
Wing, H. H. 

Creaming and aerating milk. Cornell Station Bui. 39. 
Wing, H. H. and J. A. F'oord. 

Methods of milking. Cornell Station Bui. 213. 

Woll, F. W. 

Investigations of methods of milking. Wis. Station Bui. 96. 

Chapter VII. Transportation and Sale of Milk. 

Alvord,, H. E. and R. A. Pearson. 

The milk supply of 200 cities and towns. Bur. Anim. Ind. Bui. 
46. 
Bitting, A. W. 

Source of milk supply for towns and cities. Ind. Station Bui. 89. 
Doane, C. F. 

The milk supply of 29 southern cities. Bur. Anim. Ind. Bui. 70. 
Hewlett, R. T. and G. S. Barton. 

London milk. Jour. Hyg. 1907 pages 22-31. 
Lane. C. B. 

The milk and cream exhibit at the National Dairy Show, 1906. 
Bur. Anim. Ind. Bui. 87. 
Lindsey, J. B. and P. H. Smith. 

Market milk. Mass. Station Bui. 110. 



326 

Macgregor, A. S. 

Milk supply in Copenhagen. Edinburg 1900 pages 37. 
Martiny, B. 

Milchversorgung grosserer Stadte. Zeit, Fleisch. Milchhyg. 1902 
page 259. 
Marshall, C. E. 

Milk problem from the standpoint of production. Mich. Station 
Bui. 228. 
Slack, F. H. 

Comparative value of bacterial and temperature regulations for 
a city's milk supply. Jour. Infect. Diseases Sup. pages 76-81. 
Stocking, W. A. Jr. 

Studies of market milk. Storrs Station Rpt. for 1905 page 164. 
Ward, E. G. 

Milk transportation etc. Div. Statistics Bui. 25. 
Whitaker, G. M. 

The milk supply of Boston, ]STew York, and Philadelphia. Bur. 
Anim. Ind. Bui. 81. 
Clean milk for New York City. Rpt. of N. Y. Milk Conference 1906 
pages 86. 

Chapter VIII. Dairy Refrigeration. 

Boggild, B. 

Refroidisseur pour lait. Laiterie 1895 page 137. 
Casse, F. 

Conservirung der milch durch theilweises Gefrieren. Milchzei- 
tung 1897 page 96. 
Conn, H. W. 

The relation of temperature to the keeping property of milk. 
Storrs Station Bui. 26. 
Cooper, II. 

Practical cold storage. Chicago 1905 pages 600. 
Dornic, P. 

Le froid dans le conservation du lait. Agric. Moderne. 1897 
page 458. 
Dornic, P. 

Les wagons refrigeres. Laiterie 1898 page 184. 
Girard,, A. 

Kouvelle industrie de refrigeration du lait. Jour, des Agricul 
teurs. Jan. 1898. 
Kasdorf, O. 

Eis und Kalte in Molkereibetrieb. Leipsic 1904 pages 326. 
Lane, C. B. 

The cold storage of cheese. Bur. Anim. Ind. Bui. 83. 



327 

Lorenz, H. 

Modern refrigerating machinery etc. New York, 1905 pages 390. 

Moreau, F. 

Le froid artificiel en laiterie. Rev. Ind. Lait 1901 page 1. 

Tayler, A. J. W. 

Refrigeration, cold storage and ice making machinery. London, 
1902 pages 590. 

Williams, H. 

Mechanical refrigeration. London 1903 pages 406. 

See also the periodicals "Gold Storage and Ice Trade," and "Ice and 
Refrigeration." 

Chapter IX. Pasteurization and Sterilization. 

Ashby, H. 

Some new milk sterilizers for domestic use. Lancet 1 1891 
page 360. 

Ayers, S. H. 

The pasteurization of milk. U. S. Dept. Agric. Bur. Anim. 
Ind. Cir. 184. 

Baginsky, A. 

Verwendbarkeit der durch Einwirkung holier Temperatnren dar- 
gestellten Milchconserven. Arch, fiir Kinderh. 1882 pages 
259, 397. 

Bush, E. F. 

Sterilized milk. N. Y. Med. Jour. 1891 page 719. 

Gary, C. A. 

A new milk or water sterilizer. Ala. Station Bui. 53. 

Cheesman, C. M. 

Apparatus for sterilizing milk. Med. Rec. 1889 page 39. 

Davis, E. P. 

The sterilization of milk. Ann. Gynec. Pediat, 1889-1890 page 
300. 
Emery, F. E. 

' Pasteurization of milk. N. G. Station Bui. 148. 

Farrington, E, H. and H. L. Russell. 

Pasteurization as applied to butter making. Wis. Station Bui. 69. 

Farrington, E. H. and E. G. Hastings. 

The pasteurization and the inspection of creamery and cheese 
factory by-products. Wis. Station Bui. 148. 

Freeman, R, Gr. 

Pasteurized milk as supplied to the poor etc. New York 1894 
pages 8. 



328 

Gamble, W. E. 

Sterilizing water and milk in hermetically sealed bottles. Jour. 
Amer. Med. Ass. 1894 page 386. 
Harding, H. A. and L. A. Kogers. 

Continuous pasteurizer etc. N. Y. Station Bui. 172. 

Hesse, W. 

Ueber MElchsterilisirung im Grossbetriebe. Zeit. Hyg. 1893 
page 42. 

Hope, E. W. 

Sterilization and pasteurization etc. Lancet 2 1901 page 197. 

Koplik, H. 

The sterilization of milk etc. Jour. Amer. Med. Ass. 1891 
page 548. 
Lebrun, X. 

La sterilisation du laif. Laiterie 1893 pages 17, 148. 

Leeds, A. R. 

The chemical and physical changes attendant upon the steriliza- 
tion of milk. Jour. Amer. Chem. Soc. 1891 page 34. 

Leonard, C. H. 

Infantile scurvy caused by prolonged use of sterilized food 
etc. Trans. R. I. Med. Soc. 1889-1893 page 538. 
Marshall, C. E. 

Killing the tubercle bacillus in milk. Mich Station Bui. 173. 
Marshall, C. E. 

Pasteurization of milk. Mich. Station Bui. 147. 
Monral, J. H. 

Pasteurization and milk preservation etc. Winnelka, 111. 1896 
pages 80. 
Nelson, J. 

Domestic pasteurizing methods etc. 1ST. J. Station Bui. 152. 
Rogers, L. A. 

Bacteria of pasteurized and unpasteurized milk under laboratory 
conditions. Bur. Anim. Ind. Bui. 73. 
E.omer. 

Sterilization of milk by ultraviolet light. Hyg. Rundschau 1910 
pp. 873-877. 
Rothschild, H. de 

Pasteurisation et sterilisation du lait. Paris 1901 pages 93. 
Russell, H. L. 

Effect of short periods of exposure to heat on tubercle bacilli in 

milk. Wis. Station Rpt. for 1904 pages 178-192. 
A tainted condition in pasteurized milk. Wis. Station Rpt. for 

1905 pages 222-226. 
Bacteriological examination of pasteurized milk. Wis. Station 

Rpt. for 1905 pages 236-241. 
Pasteurization of milk and cream. Wis. Station Bui. 44. 



329 

Smith, C. D. 

Pasteurization of milk. Mich. Bui. 134. 
Sommerfeld, P. 

Neuere Arbeiten ueber Kuhmilch etc. Arch, fiir Kinderh. 1890 
pages 93-136. 

Chapter X. Use of Preservatives. 

Annet. 

Boric acid and formalin as milk preservatives. Lancet 1889 
page 1282. 
Bandini, P. 

Action of formalin etc. on milk. Riv. Ig. San. Pub. (Rome) 
1906 page 23. 
Behring, E. von. 

Kuhniilchconservierung. Behringwerk Mitteilungen 1907 No. 
2 pages 25-38. , 

Bevan, E. J. 

The use of formalin as a preservative of milk samples. Analyst 
20 (1895) page 152. 
Binswanger. 

Pharmakologische Wtirdigung der Borsaure, des Borax etc. Mu- 
nich 1846. 
Chester, F. D. 

Formaldehyde in the preservation of milk. Del. Station Bui. 71. 
Chick, H. 

Sterilization of milk with hydrogen peroxide. Centrbl. Bakt. 
Par. 2nd. Abt, 1901 page 705. 
Cochran, C. B. 

Milk preservatives. Penn. Dept. Agric. Rpt. for 1899 page 277. 
Dean, H. H. and R. Harcourt. 

Butter preservatives. Ont. Agric. Coll. Exper. Farm Bui. 145. 
Doane, C. F. 

Preservatives and the food value of milk. Md. Station Bui. 86. 
Fere. 

Le borisme ou les accidents de la medication par le borax. Sem. 
Med. 1894 page 497. 
Foulerton. 

The influence on health of chemical preservatives. Lancet 1899 
page 1427. 
Hehner, O. 

Use of boric acid and formaldehyde. Brit. Med. Jour. 1899 
page 132. 
Hills, J. L. 

Preservation of milk samples. Vt. Station Rpt. for 1898 page 350. 



330 

Hoft, H. 

Solids in milk preserved with formalin. Cliem. Zeitung, 1905 
page 54. 

J ablin-Gonnet. 

Hydrogen peroxide as a preservative of milk. Ann. CJbim. Analyt. 
1901 page 129. 

Klimmer, M. 

Milk treated with formalin for calf dysentery. Zeit. Thiermed. 
1904 page 289. 

Leach, A. E. 

Inspection of milk for preservatives. Analyst 1901 page 2S9. 

Leenhouts, P. 

Preservation of samples of milk. Orgaan Ver. Ondleer. Rijks. 
Landbonw. 1900 page 195. 
Lowenstein, E. 

Influence of formalin on milk. Zeit. Hyg. Infectionsk. 1904 
page 239. 
Lukin, M. 

Hydrogen peroxide in milk. Centrbl. Bakt. Par. 2nd. Abt. 1905 
pages, 20, 165. 
Price, T. M. 

Influence of formaldehyde on the digestive enzymes. Bur. Anim. 
Ind. Rpt, for 1903 page 114. 

Richmond, H. D. and E. H. Miller. 

Preservatives in milk. Analyst 32 (1907) pages 144-154. 
Rideal, S. 

Disinfection and the preservation of food. New York 1903 
pages 494. 
Rideal, S. 

Formalin as a milk preservative. Analyst 1895 page 157. 

Rideal, S. and A. Gr. R, Foulerton. 

Boric acid and formaldehyde as milk preservatives. Public Health 
1899 page 554. 
Rivas, D. 

Formaldehyde in milk. Univ. Penn. Med. Bui. 1904 page 175. 

Rost, E. 

Borsaure als konservierungsmittel. Berlin 1903 pages 164. 

Rothschild, H. de and L. ISTetter. 

Preservation of milk with formalin. Rev. Hyg. Med. Infant. 
4 (1905) page 334. 

Schaps. L. 

Preservation with formalin. Zeit. Hyg. Infectionsk. 1905 page 

247. 



331 

Seligmann, E. 

Influence of formaldehyde on milk etc. Zeit. Hyg. Infectionsk. 
1905 page 97. 

Sherman, H. C. et al. 

Comparative experiments upon chemical preservatives in milk. 
Jour. Amer. Ohem. Soc. 27 (1905) page 1060. 

Sommerfeld,, P. 

Milk preserved with formalin. Zeit. Hyg. Infeotionisk. 1905 
page 153. 
Stenstrom, O. 

Formalin in milk according to the method of von Behring. Rev. 
Gen. Lait 1904 page 49. 
Thompson, G. S 1 . 

Preservatives, in dairy practice. Jour. Agr. Ind. South Austr. 
1900 page 969. 
Tice, W. G. and H. C. Sherman. 

Proteolysis in milk preserved with formalin. Jour. Amer. 
Chem. Soc. 1906 page 189. 
Weems, J. B. and W. W. Heileman. 

Studies in milk preservatives. Iowa Station Bui. 32. 
Weigmann, H. 

Die Methoden der Milchconservierung etc. Bremen 1893 pages 72. 
Wiley, H. W. et al 

Boric acid and borax. Bur. Chem. Bui. 84 pages 477. 
Wiley, H. W. 

Determination of effect of preservatives in foods on health and 
digestion. U. S. Dept. Agric. Yearbook for 1903 pages 289- 
302. 

Williams, R. H. and H. C. Sherman. 

Formaldehyde in milk etc. Jour. Amer. Chem. Soc. 27 (1905) 
page 1497. 
Young, A. G. 

Formaldehyde as a milk preservative. Sanitarian 43 (1899) 
page 524. 

Report, of Departmental Committee on the use of preservatives and 
coloring matters. London 1901. 

Embalming milk. Hoard's Dairyman 1899 page 167. 

Chapter XL Chemical Examination of Milk. 

Babcock, S. M. 

Use of Babcock test etc. Wis. Station Buls. 31, 36. 

Babcock and Farrington. 

New and improved tests of dairy products. Wis. Bui. 195. 



332 

Oathcart, E. P. 

Reduction of methylene blue by cow's milk. Jour. Hyg. 1906 
page 300. 

Evans, J. R. 

A laboratory handbook for the analysis of milk etc. 1905 pages 60. 

Farrington, E. EC. and F. W. Woll. 

Testing milk and its products etc. Madison, Wis. 1904 pages 
269. 

Gerber. 

Die praktische Milchpriifung. Bern 1900. 

Hoppe-Seyler. 

Handbuch der physikal-chem. Analyse. Berlin 1893. 

Jordan, W. H. 

Inspection of Babcock milk test bottles. 1ST. Y. Station Bui. 178. 

Leffman, H. 

Analysis of milk and milk products. Phil. 1905 pages 78. 

Leffman, H. and W. Beam. 

Analysis of milk and milk products. Phil. 1896 pages 120. 

Miill&r, C. 

Anleitung zur Priifung von Kuhmilch. Bern 1883. 

Reichelt. 

Die Milchprufungsmethoden. Bremen 1899. 

Richmond,, H. D. 

Dairy chemistry. London 1899 pages 384. 

Richmond,, H. D. 

The laboratory book of dairy analysis. London 1905 pages 90. 

Schoenman, A. 

Milk testing. Madison, Wis. 1895 pages 42. 

Snyder. H. 

Dairy chemistry. New York 1906 pages 190. 

Sommerfeld's Methods for the examination of milk, translated by A. 
T. Peters and R. S. Hiltner, Chicago 1900. 

Van Slyke, L. L. 

Modern methods of testing milk etc. New York 1906 pages 214. 

Weber, E. 

Die zur Unterscheidung roher und gekochter Milch LTntersuch- 
ungsmethoden etc. Leipsic 1902 pages 136. 

Webster, E. H. 

Fat testing of cream by the Babcock method. Bur. Anim. Ind. 
Bui. 58. 



333 

Chapter XII. Bacteriology of Mijlk. 

Adametz, L. 

Bacillus lactis viscosus. Landw. Jahrb. 20 (1891) pages 185- 
207. 

Barthel, C. 

Bakteriologie des Meiereiwesens. Leipsic 1901. 

Bergey, D. H. 

The source and nature of bacteria in milk. Harrisburg, Pa. 1904 
pages 40. 
Berliner, E. 

The milk question from various points of view. 1907 pages 28. 
Buege, A. W. E. 

Ueber die Untersuchung der Milch auf Tuberkelbacillen. Halle 
1896 pages 19. 
Conn, H. W. 

Fermentations of milk. Office Exper. Stations Bui. 9 pages 75. 
Conn, H. W. 

Classification of dairy bacteria. Storrs Station Rpt. for 1899 
pages 13-68. 
Conn, H. W. 

Agricultural bacteriology. Phil. 1901. 
Conn, H. W. 

Bacteria in milk and its products. Phil. 1903 pages 306. 
Conn, H. W. and W. M. Esten. 

Comparative growth of different species of bacteria in normal 
milk. Storrs. Station Rpt. for 1901 pages 13-80. 
Conn, H. W. et al. 

A classification of dairy bacteria. Storrs Station Rpt. for 1906 
pages 91-203. 
Dinwiddie, R. R. 

Milk, its decomposition and preservation. Ark. Station Bui. 45. 
Eckles, C. H. and S. E. Barnes. 

Bacteriological study of the college creamery milk supply etc. 
Iowa Station Bui. 59. 
Ereudenreich, E. von. 

Dairy bacteriology, translated by J. R. A. Davis. London 1900 
pages 144. 

Harrison, F. C. 

The bacterial contamination of milk and its control. Can. In- 
stitute Trans. 1904 pages 467-496. 

Heinemann, P. G. 

The kinds of lactic acid produced by lactic bacteria. Jour. Biol. 
Chem. 2 (1907) pages 602-612. 



334 

Heinemann and Glenn. 

Germicidal action of milk. Jour. Infect, Diseases 1908 pp. 
534-541. 

Houston, A. C. 

The bacteriological examination of milk etc. London 1905 
pages 48. 
Hunziker, O. F. 

Germicidal action in cow's milk. N. Y. Cornell Bui. 197. 

Kolle, W. 

Milchhygienische Untersuchungen. Jena 1904 pages 32. 

Lewis, L. L. 

Bacterioloo'y of milk. Okla. Station Bui. 40. 

u«/ 

MacConkey. A. 

Bacteriology of milk. Jour. Hyg. 190G page 385. 

Marshall, C. E. 

Associative action of bacteria in souring milk. Mich. Special 
Buls. 29 and 33. 
Moore, V. A. 

Inefficiency of milk separators in removing bacteria. U. S. Dept. 
Agric. Yearbook for 1895 pages 431-444. 

Moore, V. A. 

Bacteria in milk etc. Albanv 1902. 
Painmel, L. H. 

Notes on dairy bacteriology. Iowa Station Bui. 34. 

Park, W. H. 

The great bacterial contamination of the milk of cities etc. Jour. 
Hyg. vol. 1 page 391. 

Pernot, E. F. 

Stagnant water germs in milk. Oreg. Station Bui. 71. 

Ravenel, M. P. 

Milk supply from the bacteriological standpoint. Phil. 1898 

pages 7. 
Rosenau, M. J. and G. W. McCoy. The germicidal property of milk. 

Jour. Med. Research. March 1908. 

Rothschild, H. de 

Le lait etc. Paris 1903 pages 90. 

Russell, H. L. 

Outlines of dairy bacteriology. Madison, Wis. 1905 pages 199. 

Stewart, A. H. 

Bacteria in certified milk. Amer. Jour. Med. Sci. 1906 page 625. 

Stocking, W. A. Jr. 

The so-called germicidal property of milk. Storrs Station Bui. 37. 

Swithinbank, H. and G. Newman. 

Bacteriology of milk. London 1903 pages 605. 



335 

Torrey. 

Bacteria in bottled milk. Jour. Infect. Diseases 1910 pp. 377- 
392. 
Ward, A. R 

Invasion of the udder by bacteria. Cornell Station Bui. 178. 
Proceedings of the American Association of Medical Milk Commis- 
sioners, 1908. 

Chapter XIII. Transmission of Infectious Diseases by Milk. 

Adametz. 

Die Bakterien in normaler nnd abnormaler Milch. Oester. 
Monatsh. Tierheilk. und Tierzncht, 1890 pages 1-36. 
Ashby, A. 

Diphtheria from milk. Public Health. 1906 page 145. 
Auerbach, B. 

Ueber Verbreitung des Typhus durch Milch. Dent. Med. Wo 
chensc. 1884 page 709. 
Ballard, E. 

Typhoid and milk. Lancet 1873 page 492. 
Bang. 

Eutertuberculose der MRlchkiihe etc. Deut. Zeit. Tiermed. verg- 
leich. Path. 1885 page 45. 
Beach, C. L. 

History of a tuberculous herd of cows. Storrs Station Bui. 24. 
Behring, E. von. 

The suppression of tuberculosis etc.. translated by C. Bolduan 
1904 pages 85. 
Behring et al. 

Milk and tuberculosis. Beitr. exper. Ther. 1902. 
Bell, O. H. 

On the propagation of scarlet fever. Lancet 1870 page 598. 
Besse, P. 

Human and bovine tuberculosis. Arch. Med. Exper. Anat. P^th. 
1904 pages 375-387. 
Blumenthal, F. 

Producte der bacterischen Zersetzung der Milch. Virch. Arch, 
vol. 146 page 65. 
Brieger and Ehrlich. 

Uebertragung von Immunitat durch Milch. Deut. Med. Wo- 
ollens. 1892 -page 393. 
Cary, C. A. 

Dairy and milk inspection. Ala. Station Bui. 97. 
Coleman, O. 

Spread of throat illness by milk. Pub. Health 1899 page 2i. 



336 

Conn, H. W. 

Relation of bovine tuberculosis to that of man etc. Starrs Sta- 
tion Bui. 23. 

Dawson, C. F. 

Vitality and retention of virulence by certain pathogenic bacteria 
in milk etc. Bur. Anim. Ind. Rpt. for 1898 pages 224-228. 

Dieckerhofr". 

Schutzmassregeln gegen die Verbreitung der Maul — und Klauen- 
seuche durch Magermilch-Ber. Tier. Wochensc. 1891 page 109. 

Dorset, Ml. et al. 

Experiments concerning tuberculosis. Bur. Anim. Ind. Bui. 52. 

Ernst, H. C. 

How far may a cow be tuberculous before her milk becomes dan- 
gerous? Mase. Station (Hatch) Bui. 8. 

Petting. 

Zur Bekampfung der Maul-und Klauenseuche durch abgokochte 
Milch. Ber. Tierarz. Wochensc. 1900 page 183. 

Freeman, R. G. 

Milk as an agency in the conveyance of disease. N. Y. Med. 
Rec. 1906 page 433. 
Glage. 

"Eitrige Mastiten. Zeit, Fleisch Milchhyg. 1903. 
Groning. 

Streptokokken bei Euterentzundungen. Inaug. Diss. Bern 1901. 
Hart, E. A. 

A report on the influence of milk in spreading zymotic disease. 
Brit. Med. Jour. 1897 pages 1167, 1229, 1292. 
Hill, B. 

Mlilk scarlatina. Pub, Health. 1890 page 487. 
Hohne. 

Heftige Diarrhoe bei Menschen nach dem Genusse von Colostrum. 
Ber. Archiv. 1889 page 478. 
Jamieson, J. 

A milk epidemic of typhoid fever. Pub. Health 1901 page 655. 
Kitasato, S. 

Das Verhalten der Cholerabakterien in der Milch. Zeit. Hyg. 
vol. 5 page 491. 
Klein. 

Pathogenic microbes in milk. Jour. Hyg. vol. 1 pages 78-95. 
McVail, J. C. 

Milkborne typhoid. Brit. Med. Jour. 1896 page 217. 
Malkmus, B. 

Handbuch der gerichtlichen Tierheilkunde. Hanover 1906 page 

687. 



337 

Mohler, J. H. 

Infectiveness of milk of cows which have reacted to tuberculin 
test. Bur. Anim. Ind. Bui. 44. 

Mohler, J. H. and H. J. Washburn. 

A comparative study of tubercle bacilli from varied, sources. Bur. 
Anim. Ind. Bui. 96. 

Mjonatzkow. 

Ueber die Veranderungen der Milch bei Impfmilzbrand. Inaug. 
Diss. St. Petersburg 1881. 
Ostertag, R. 

Die Regelung der Milchversorgung mit Hinsicht auf uebertrag- 
bare Krankheiten. Zeit. Fleisch Milchhyg. vol. 2 page 8. 
Ostertag, R. 

Die Virulenz der Milch von Kiihen welche lediglich auf Tuber- 
kulin reagierten. Zeit. Fleisch Milchhyg. vol. 9 pages 168, 
221. 

Raw, K 

Human and bovine tuberculosis. Brit. Med. Jour. 1904. pages 
907-909. 
Rouvier, J. 

Le lait ; caracteres dans l'etat de sante et de maladie etc. Paris 
1893 pages 344. 
Russell, H. L. 

The spread of tuberculosis through factory skimmilk. Wis. Sta- 
tion Bui. 143. 
Russell, H. L. and E. G. Hastings. 

Infectiousness of milk from tubercular cows. Wis. Station Rpt. 
for 1904 pages 172-177. 
Salmon, D. E. 

Relation of bovine tuberculosis to the public health. Bur. Anim. 
Ind. Bui. 33. 
Salmon. D. E. and T. Smith. 

Tuberculosis of cattle. Bur. Anim. Ind. Circ. 70. 
Schroeder, E. C. and W. E. Cotton. 

Experiments with milk artificially infected with tubercle bacilli. 
Bur. Anim. Ind. Bui 86. 
Schroeder, E. C. and W. E. Cotton. 

The relation of tuberculous lesions to the mode of infection. Bur. 
Anim. Ind. Bui. 93. 
Schroeder, E. C. and W. E. Cotton. 

The danger from tubercle bacilli in the environment of tubercu- 
lous cattle. Bur. Anim. Ind. Bui. 99. 

Scott, J. M. 

Tuberculosis in cattle and, tuberculin tests of the station herd. 
K M. Station Bui. 55. 



338 

Sinclair, J. 

Milk supply and the public health etc. Dundee 1901 pages 36. 

Tower, F. J. 

Milk inspection. Med. News 1891 page 151. 

Veeder, M. A. 

The spread of typhoid and dysenteric diseases by flies. Med. Rec. 
1898. 

Watson, I. A. 

Milk from a sanitary standpoint. Manchester, N. H. 1887 
pages 15. 

Welply, J. J. 

Creameries and infectious diseases.. Lancet 1894 page 992. 

Williams, E. M. N. 

Diphtheria and milk supply. Lancet 1 1900 page 132. 

Wiirzburg, A. 

Leber Infektionen durch Milch. Ther. Monatsh. 1891 page 18. 

Zschokke. 

Beitrag zur Kenntniss des gelben Galtes. Landw. Jahrb. Schweiz. 
1893 page 200. 

Chapter XIV. Infant Feeding. 

Abbott, S. W. 

Infant mortality in Mass. Jour. Mass. Assoc. Boards of Health 
VIII. No. 4, Dec. 1898. Boston, pp. 19. 

Adams, S. S. 

The evolution of pediatric literature in the United States. Arch. 
of Pediatrics, New York. 1897. Vol. XIV. 

Adriance, V., and Adriance, J. S. 

A clinical report on the chemical examination of 200 cases of 
human breast milk. Arch, of Pediatrics, New York, 1897. 
. Vol. XIV, pp. 22-45, 85-102. Tab. 1-5, Charts 1-5. 

Baldwin, Helen. 

An experimental study of oxaluria, with special reference to its 
fermentative origin. Journ. Exper. Medicine, Vol. V, 1900- 
1901, pp. 27-46, Fig. 1, Tabs. X. 

Baner, W. L. 

The Home Modification of milk. N. Y. Med. Journ. Mch. 12, 
1898, V. 67, pp. 345-348. 

Biedert, P. 

Neue Lntersuchungen u klin. Beobacht, iiber Menschen- u Kuh- 

milch als Kindernahrungs mittel. Virchow's Arch. f. path. 

Anat. in phys. u fur klin. Med., Bd. 60, 1874, pp. 352-379. 



339 

Boggs, T. R. 

A simple method for the quantitative determination of proteids 
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345 



INDEX. 



abnormal milk, 32-52 

abortion, 64 

acidity, determination of, 188 

actinobacillosis, 65 

actinomycosis, 65 

actinomycosis in milk, 261 

Adams method for fat, 184 

adulteration of milk, 52 

aerating milk, 129 

afterbirth, retention of, 88 

age of cow and milk fat, 18 

air, examination of, 249 

albumin, determination of 186 

alcoholic fermentation in milk, 39 

alkalinity of human milk, 286 

ammonia for cooling milk, 154 

anthrax, 66 

anthrax, carried by milk, 259 

antitoxins^ in milk, 45 

areometer test, 183 

ash, determination of, 187 

ash of milk, 16 

Babcock asbestos method, 184 

Babcock test, 182 

bacteria, affected by temperature, 239 

antagonism among, 241 

classification of, 198, 211 

extent of milk contamination, 237 

growth in milk, 242, 245 

in milk, 8 

in milk, sources of, 205 

list of in milk, 213-237. 

pathogenic in milk, 213 

rate of multiplication, 240 

reducing number in milk, 241 

reproduction of, 202 
bacteriological examination, 246 
bacteriology of milk, 198-250 
barley for cows, 99 
barley water for infants, 287 
barnyards, 111 

barnyards, bacteria from, 209 
bedd'ng, bacteria in, 209 
bedding for cows, 55, 110 
benzoic acid in milk, 175 
bibliography of milk, 316-343 



bitter milk, 38 

blackleg 66 

blended milk, 27 

bloating, 67 

bloody milk, 42 

blue milk, 33 

borax in milk, 171 

boric acid in milk, 171 

Boston, milk supply of 144 

bran for cows, 99 

breed of cow and milk fat, 17 

brewers' grains for cows, 100 

brine for cooling milk, 153 

buckwheat for cows, 100 

buildings, 106-115 

butter, 299 

cold storage of, 159 

standard, 298 
buttermilk for infanta, 289 

standard, 297, 306 

carbonated milk, 29, 307 
care of cows, 54 
casein, 7, 15 

determination of, 185 
certified milk, 25, 28 
charities and milk for infants, 295 
cheese, 302 

cold storage of, 159 
chemical examination of milk, 177-197 
chemistry of milk, 14 
cholera from milk, 270 
chromatea in milk, 175 
cities, milk supply of, 141-149 
clarified milk, 29 
cleanliness in milking, 119 
cohesive power of milk, 13 
cold' storage, 159 
color, detection of, 191 

of milk, 11, 33 
colostrum, 18 
composition of milk, 14 
condensed milk, 29, 303 

by freezing, 160 

Standard, 297 
cooling milk, 129, 137 
cooperation in milk business, 147 



346 



corn for cows, 100 
cornstalk disease, 68 
cast of producing milk, 3 
cotton seed for cows, 100 
covered pails, 128 
cow pox, 69 

carried by milk, 260 
cream, 298 

sampling, 180 
creaming of milk, 13 
culture media for bacteria, 248 

dehorning, effect on milk, 23 

densimetric method, 184 

density of milk, 13 

desiccated milk, 29 

dextrinized gruel for infants^ 288 

diarrhea from milk, 271 

diluents of milk for infants, 287 

diphtheria from milk, 269 

dirt in milk, 51 

dirt test, 194 

diseases, carried by milk, 251-272 

of cows, 53-98 
disinfection of .stables, 59 
drugs, effect on milk, 43 

electrical pasteurization of milk, 204 
resistance of milk, 13, 203 

enteritis, 69 

enzymes in milk, 8 

estrum, effect on milk, 20, 47 

evaporated milk, 29 

excitement, effect on milk, 21 

exercise, effect on milk, 20 
for cows, 53 

fat, determination of, 182 

testing for, 194 
feed, effect on milk, 21, 35 
feeding cows, 54, 99-105 
fermentations, abnormal in milk, 244 
filtering milk, 129 
flavors in milk, 34, 37 
fluke worms, 70 
fluorids in milk, 175 
foot-and-mouth disee.se, 71 

carried by milk, 257 
foot rot, 72 
foremilk, 127 
formaldehyde in milk, 169 
freezing point of milk, 13, 150 
frozen milk, 157 
fruits for cows, 102 



galactase, 9 

galactin, 16 

garget, 77 

gelatine, detection of, 194 

Gerber's acidobutyrometer, 183 

fermentation test, 193 
germicidal property of milk, 10, 210 
gestation effect on milk, 23 
grains for cows, 99 
grooming cows, 54, 119 
guaranteed milk, 28 

heated milk, detection of, 192 
Hegelund method of milking, 121 
hematuria, 72 
hemorrhagic enteritis and milk, 263 

septicemia, 73 
history of milk inspection, 308-315 
homogenized milk, 29 
horn fly, 73 
human milk, 276 
humanized milk, 28 
hydrogen peroxid in milk, 173 
hygiene of cows, 53-98 

ice cream, 306 

ice for cooling milk, 152 

individuality of cows, 18 

infants, feeding, difficult case, 291 

methods, 283 

simple case, 289 

with milk, 273-296 

motality of, 273 
inspected milk, 26 
inspection of buildings, 114 

of milk, history of, 308-315 

jaundice, 74 
joint ill, 74 

kafir corn for cows, 100 
kephir, 305 
keratiti 75 
koumiss, 305 

lactalbumin, 15 

lactoglobulin 16 

lactometer 181 

leben, 306 

leucocytes in milk, 9, 47 

lice, 75 

lin.seed meal for cows, 100 

liquefying bacteria, 212 

literature on milk, 316-343 



347 



malignant catarrhal fever, 76 

edema, 77 
mammitis, 77 

and milk, 262 
mange, 90 
market milk. 25 

examination, 178 
matzoon, 305 
metritis, 79 
milk, abnormal, 32-52 

and infants, 273-296 

bacteria in, 8 

biology of, 5 

care of, 136 

cars, 141-149 

comparison of human and bovine, 
281 

contaminated in handling, 209 

definition, 5 

fat, 7, 14 

fever, 79 

and milk, 263 

inspection, history, 308-315 

normal, 5-31 

of various animals, 30, 31 

pails., 128 

poisoning, 46 

powder, 304 

products and health, 297-307 

rooms, 112 

secretion, 6 
milk sickness, 81 

in milk, 261 

sugar, 7 

by freezing, 160 

determination of, 186 

utensils, care of, 133 
milk-borne diseases, 265 
milkers, health of, 116 
milking and handling milk, 116-140 ' 
milking machines, 123 

methods, 120 
mixing milk, 23 
modified milk, 28 
mother's milk, 276-281 
municipal control of milk, 295 
mycosis, 81 

nagana, 82 

nephritis, 82 

New York, milk supply of, 142 

nodular disease, 83 

nutrose. 305 



oatmeal water for infants, 288 

odor of milk, 12 

odors in milk, 34, 37 

osteomalcia, 83 

paper coil method, 184 

parturient apoplexy, 79 
pasteurization, effect on milk, 164 

of milk, 162-168 

of milk for infants, 293 
pasteurized milk, 26, 29 
pathogenic bacteria in milk, 213 
peptonized milk for infants, 287 
pericarditis, 84 
peritonitis, 84 

Philadelphia, milk supply of, 145 
plasmon, 305 
pleuro-pneumonia, 85 

in milk, 261 
poisonous plants, effect on milk, 44 
poisons, 85 
preservatives, detection of, 189 

in milk, 169-176 
proprietary feeds, 104 
ptomairus in milk, 46 
purifying milk, 129 
pycnometer, 182 

rabies, 87 

in milk, 260 
rations for different climates, 104 

narrow and wide, 100 

size of, 101 
reaction of milk, 14 
red milk, 34 

refractive index of milk, 13 
refractometer, 185 
refrigeration of milk, 150-161 
rheumatism, 88 
rice water for infants, 287 
rinderpest, 89 
ringworm, 89 
roots for cows, 102 
ropy milk 39 
roughage for cows, 103 

saccharine in milk, 175 
sale of milk, 141-149 
salicylic acid in milk, 175 
salt for cows, 59 
samples, taking of, 178 
•sanitary milk, 29 
sanose, 305 
scabies, 90 



348 



scarlet fever from milk, 268 
scouring, 91 
screw-worm fly, 91 
seasons, effect on milk, 21 
septic diseases and milk, 264 
sewage, disposal of, 111 
.shelter, effect on milk, 23 
silage, 102 » 

skim milk, 299 

standard, 297 
slimy milk, 39 
soapy milk, 38 

sodium carbonate in milk, 174 
solids, determination of, 185 
soiling, 102 

sore throat from milk, 263 
souring of- milk, 242 
spaying, effect on milk, 20 
specific gravity of milk, 11, 181 

heat of milk 12, 150 
stables, 106 
staggers, 92 
standard milk, 27 
standards, legal for milk, 24 

of milk products, 297 
starch, detection of, 194 
sterilization of milk, 162-168 
sterilized milk, 29 
stomach worms, 92 
stomatitis, 92 
straining milk, 129 
streptococci in milk, 245 
succulent feeds, 101 
sunlight, effect on bacteria, 203 



teat diseases, 93 £ 

temperature, effect on bacteria, 239 

testing cows, 177 

tetanus in milk, 261 

Texas fever, 94 

thrush from milk, 271 

time of milking and' milk fat, 19 

toxins in milk, 45 

transmission of disease in milk, 251-272 

transportation of milk, 141-149 

tuberculosis, 95 

carried by milk, 251, 271 
tumors, 96 

typhoid fever from milk, 266 
tyrotoxicon, 46 

udder diseases, effect on milk, 40 
udder of cow, 5 

ventilation of stables, 108 
verminous bronchitis, 97 
viscosity of milk, 11 

warble fly, 97 

water, bacteria in, 209 

examination of, 249 

for cooling milk, 151 

for cows, 55 

in milk, 192 
weather, effect on milk, 20 
weighing milk, 177 
wet nurse, requirements, 281 
whey mixtures for infants, 286 
wounds, 98 

yellow milk, 34 
yoghurt, 307 



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